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Ask the Vet, Sallie S. Hyman VMD, DACVIM

  • What do I do for an Equine Runny Nose?

    Your horse has a snotty nose.  It's as plain as the, well, snot, all over his nose, front legs and wherever else ha can wipe it on.  Yuck!

    Determining the source and cause of nasal discharge can be a challenge to diagnose in the horse due to the complicated anatomy of the their skull. the horse has two main sinus cavities (frontal and maxillary) in the head, as well as several smaller ones.  The upper back molars communicate with the sinuses.  The main sinus communicates with the nasal passages.  It is a complex and intertwined system that can lead to much confusion in trying to figure out where all of that snot is coming from.

    When you first discover the nasal discharge, take note of a few things:

    What color is it?

    Does it come from one or both nostrils?

    Does it have an odor?

    Does your horse have a fever?

    Is he lethargic?

    Have an appetite?

    Next, think about whether or not your horse has been exposed to any other horses:

    Have you been to a show?

    Are their new additions in the stable?

    Are there any sick horses in contact with yours?

    This information will help your veterinarian better diagnose the cause of your horses symptoms.

    The common causes of nasal discharge include strangles, sinus infections, tooth problems, and guttural pouch infections. Bilateral (both nostrils) occurs when the source of the mucus is distal to the nasal openings.  This would include strangles and guttural pouch infections.  Unilateral discharge (one nostril) occurs when the mucus comes from the opening in the nasal passage, such as with a sinus infection, or a tooth root problem. When it is a tooth root problem, the discharge generally has a foul odor.

    To accurately diagnose the problem, your horse will likely need to have an endoscopic exam and/or radiographs, as well as blood work, and cultures.

     In an endoscopic exam, a small thin tube with a camera on the end is inserted up the nose.  This allows the vet to see the nasal passages, the opening of the maxillary sinus in the the nasal passages, the guttural pouches and the trachea.  This can help determine where, exactly, the mucus is coming from.

     A radiograph (x-ray) can show fluid within the sinus or guttural pouches.  In severe cases of gutteral pouch infections small concretions of mucus, called chondroids, develop.  These can be seen via radiograph. A radiograph can also be used to evaluate tooth root abscesses, cracked or broken teeth, or a tooth that is completely worn down. 

    Blood work can confirm the infection via a white blood count and fibrinogen.  A special blood test can be used to test for strangles.

    Finally, a sample of the discharge may be taken from the nasal passage, the guttural pouches, the sinus, or from the trachea.  This can be can be used for a culture, in which the veterinarian can grow whatever bacteria may be lurking in your horse's nose. 

    Once you have a diagnosis, you and your veterinarian can plan a course of treatment.  Strangles is often left to run its course, unless the horse is in severe distress.  Antibiotics are given in this case.  Sinus and guttural pouch infections usually require long term antibiotic therapy and sometimes flushing the sinus or pouches.  A tooth root problem is also treated with antibiotics, flushing the sinus, and properly treating the tooth.  Most of the time, the tooth will need to be removed and the hole packed with dental cement. Treatment is very rewarding in most cases!  Some severe cases of sinus, guttural pouch, or tooth problems may require surgery.  Fortunately, these are the exceptions.

    Once again, having a little knowledge will help you to help your house when illness strikes.  Being able to provide information to your veterinarian will help speed the diagnosis process and get your horse on the right course of treatment in a timely manner. 

    Registered 2011 Equestrian Collections; Author:  Sallie S. Hyman,  VMD, DACVIM, CVA 

  • How do I Handle a Vaccine Reaction?

    Vaccine Reactions

    Occasionally a horse will have a reaction at a vaccination site. This will usually occur within twelve to twenty-four hours after a vaccination.  Common reactions symptoms included lethargy (feeling tired), heat, pain, and /or swelling at the vaccination site, fever, loss of appetite, stiff neck, and unwillingness to put the head down to graze or eat from the ground. 

    These reactions are usually to the adjuvant in the vaccine (the part of the vaccine that helps to stimulate the immune system) not to the agent (bacterial or viral) that you are vaccinating against.  With the advent of newer adjuvants, these reactions are becoming less frequent.  Combination vaccines also help to decrease the amount of adjuvant that your horse is exposed to by decreasing the overall numbers of shots he receives.  Still, some horse will react no matter what. 

    What should you do if your horse has any of these symptoms?

    First, call your veterinarian and let them know your horse had a reaction.  This is important information for your vet to have in your horse's record.  Next time, the vet may try a different brand of vaccine next time, or perhaps try a different vaccine site.  The vet can also keep track of how many horses have reacted to a certain vaccine and report this information back to the vaccine manufacturer.  Input from horse owners and veterinarians helps to drive quality control and improve vaccine performance and safety.  

    Your veterinarian may advise you to give your horse a dose of a non-steriodal anti-inflammatory agent such as flunixin meglumin (Banamine®) or firocoxib (Euioxx®).  Carefully follow the dosage and time schedule your veterinarian advises.

    Next, do what you can to make your horse comfortable.  If your hose is sore at the injection site, you can put a warm compress on the area.  Be careful not to make it too hot! You can do this one to two times a day.  This is also very helpful if the area has become an abscess. Place your horse's feed, hay, and water at a level that is comfortable for him.  You can do this by placing them on an overturned muck tub, or hay bales, or hanging a hay net, whatever gets it to the right height.

    What about complications?

    If the vaccination site turns into an abscess, have your veterinarian examine your horse. An ultrasound may be performed to see how large the abscess is, where it is located, and how much fluid is present. If may be necessary to drain the abscess with a needle or to make a small incision to open it up.  A sample of the fluid can be collected at  that time for analysis and culture.  Antibiotics may be prescribed.  Luckily, most resolve without major incident.

    Vaccination is an important part of keeping our horses healthy.  The benefits far outweigh the occasional vaccine reaction occurrence.  However, if it does occur, you now have the knowledge to handle the situation.

    Registered 2011 Equestrian Collections; Author:  Sallie S. Hyman,  VMD, DACVIM, CVA  

    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional.  In particular, all horse owners should seek advice  and treatment from a licensed veterinarian for their horses' medical care.         


  • What About Joint Supplements?

    We ask our horses to participate in a variety of athletic endeavors, from reining and dressage, to racing and jumping.  All of these activities put stress and strain on their joints.

    To understand how joint supplementation may help you horse, you need to know a bit about the make-up of the equine joint. 

    The equine joint is made up of the articular cartilage, the synovial fluid (joint fluid) and the soft tissue structures that hold the joint together (capsule and ligaments).  The articular cartilage and the synovial fluid are very important:

    The articular cartilage is made up of chondrocytes (cartilage cells) that reside with a matrix.  The matrix is made up of proteoglycans, collagen, and elastin.  The proteoglycans are made up of a core strand of hyaluronic acid with branches of glycosaminoglycans (GAGs).  Water sticks tot the GAGs and gives the cartilage resistance to pressure.   

    The synovial fluid contains two main components.  The first is the fluid part.  It is produced from filtrated blood plasma.  The second component is hyaluronic acid.  It is produced by cells of the synovial lining of the joint capsule.  The joint fluid acts as a shock absorber, decreases friction, supplies oxygen and nutrients to the chondrocytes, and removes waste.  

    When these is stress or wear and tear on these structures, inflammation develops.  The inflammatory factors degrade the structures and quality of the cartilage and joint fluid.  Normally, the joint is able to respond by producing new joint fluid and cartilage cells.  If this process is overwhelmed, then permanent damage can occur, thus producing an unhealthy and sometimes painful joint.

    What can a horse owner do?

    As horse owners, we would like to be able to decrease the stress and inflammation in our horses' joints and help make them healthier.  There are several oral supplements that can be used to do just that.  These supplements contain ingredients that are part of the make up of either the articular cartilage or the synovial fluid.  There are also supplements that act as anti-inflammatories.  For more advanced disease, there are prescription only treatments available from your veterinarian.   

    Does Joint Supplementation Really Work?

    The research in both humans and horses has been varied in its findings.  Some reports have shown improvements while others have shown no effect.  Fortunately none have shown any harm.  Many horse owners report anecdotal evidence that supplementation works. Some horse owners are concerned about feeding their insulin resistant horses products containing glucosamine, a type of sugar.  There is little to no risk in giving glucosamine to a horse with insulin resistance.  In fact, it may help by making him more comfortable to be exercised, thus helping him to lose weight.  

    What Ingredients should I Look for in a Joint Supplement?

    Here are the ingredients to look for and some products that contain them:
    Chondroitin Sulfate has been shown to decrease swelling in joints.  It acts by decreasing the amount of destructive enzymes in the joints.  It can also decrease certain biomarkers of inflammation in synovial fluid.  As a component of proteoglycans, it is a building block of cartilage.  It works synergistically with glucosamine.

    Glucosamine is a natural compound found in healthy cartilage.  It is a precursor in the production of proteoglycans in the cartilage matrix and synovial fluid.  Glucosamine is believed to strengthen cartilage.  It is constantly broken down and resynthesized in normal joints.  Works synergistically with Chondroitin Sulfate. 

    Hyaluronic Acid (HA) is a main part of the make-up of synovial fluid and articular cartilage.  It increases the lubrication of the soft tissue structures in the joint and increases the viscosity of joint fluid, while decreasing inflammation in the joint by scavenging free radicals.  Supplementation may induce the body to product more of its own HA. 

    Methylsulfonlmethane (MSM) contains sulfur in a form that the body can use.  Sulfur is necessary for the formation of collagen, glucosamine, and chondroitin, all components of cartilage.  It may also decrease pain and inflammation.

    Many products use combinations of Chondroitin, Glucosamine, HA, and MSM to provide all the necessary building blocks:

    Other products are made with Green Lipped Mussels (Perna Canaliculus) that provide GAGs; Vitamin C, an antioxidant that scavenges free radicals;  Maganese, needed to make joint fluid and cartilage; and anti-inflammatories such as Yucca.

  • How Hot is too Hot?

    When is it too hot to safely ride my horse?

    Knowing how your horse thermo-regulates will help you better understand how to keep him cool. Horses' bodies produce heat when they work. They have several mechanisms that get rid of this heat.

    The most important mechanism is evaporation. Most heat is generated from a horse's large muscle mass. The cardiovascular system (the heart and blood vessels) move the heat from the muscles and organs to the skin. As your horse works, he produces sweat in glands in his skin. This sweat is composed of water and electrolytes (sodium, chloride, potassium, and calcium). As the sweat evaporates, it dissipates large amounts of heat, thus cooling your horse. To give you an idea of how much a horse needs to sweat to keep cool, the amount of heat dissipated by one liter of sweat equals just one to two minutes of maximal exercise, or five to six minutes of sub maximal exercise!

    Other mechanisms include breathing out some of the heat through respiration. As your horse exercises, his respiration increases, thus releasing heat. Additionally, some heat is lost through convection/radiation where heat is moved directly from the skin to the environment.

    Keeping these mechanisms in mind, there are several things you can do to help your equine partner stay cool:

    1. Provide plenty of clean water. Your horse needs to replace that sweat! Make sure the water is clean and not too warm. Some horses are particular about water temperature.
    2. Get your horse fit. An overweight horse has a harder time moving the heat through all that fat.
    3. Hose or sponge your horse with COLD water over the large vessels on the inside of the hind legs, belly, and neck. These vessels bring the heat to the surface, so you want to cool those areas. Be sure to scrape off the water as it will warm quickly. There are many Icing and Cooling products that can help.
    4. Work in the morning or early evening when it is cooler
    5. Provide shade. A run-in or trees are just fine!
    6. Clip any horse with a heavy hair coat
    7. Replace electrolytes lost in sweat. Summer Games Electrolytes, or Farnam Apple Dex, are good choices.
    8. Keep your horse in a well ventilated stall with a fan. Remember that evaporative cooling? The fan will help! (Be sure cords are out of reach and plugged into a ground fault interrupter)
    9. Put sunscreen or zinc oxide on any pink or white noses. 
    10. Provide a water misting system if possible (again .. it helps with evaporative cooling!)

    Sometimes we can't avoid the heat. On those days, keep an eye on the Heat Stress Index. The Heat Stress Index is the sum of the temperature plus the humidity. For example: if the temperature is 80 degrees Fahrenheit and the humidity is 20%, then the Heat Index is 100 (80+20=100). If the Heat Stress Index is less than 120, it is ok to ride. Start watching it as it rises above 120, at 150 your horse's cooling system won't work effectively. If it is greater than 180, your horse will be unable to thermo-regulate.

  • Barn Biosecurity. Why it matters!

    By now, most horse owners heave heard about the outbreak of Equine Herpes Virus that occurred at the Cutting Horse event in Ogden, UT. We are truly saddened by the loss of life. Infectious diseases are always a risk when large numbers of horses congregate for competitions. What we can take away from this tragedy are ways to implement biosecurity practices to keep our horses and farms safer from infectious disease.

    What is Biosecurity?
    Biosecurity consists of the principles, actions, precautions and protocols that protect the health of animals by preventing the transmission of disease through physical barriers and hygiene practices.

    Why Does Biosecurity Matter to the Horse Owner?
    A well planned and carried out biosecurity program will reduce your personal costs due to animal illness. On a larger scale, biosecurity promotes a stronger industry overall by preventing the shutdown of farms/events/transportation. Many reportable and foreign animal diseases have been stopped from becoming a larger problem by farm owners recognizing that something was not right, implementing good biosecurity, and seeking veterinary advice.

    How Do I Establish a Biosecurity Program?

    A lot of biosecurity is really just good, common sense practices:
    1. Avoid traveling with horses that suspect have an infectious disease
    2. Avoid traveling with horses that have been exposed to infectious disease (even if they do not seem ill)
    3. In the event of an outbreak, quarantine ALL horses on the premises until the horses are cleared by a veterinarian
    Routine practices are critical:
    1. Quarantine all new horses for 2-3 weeks before co-mingling them with other horses
    2. Vaccinate all horses based on the recommendations of your local vet
    3. Practice good hygiene when handling horses - washing hands between handling sick and well horses, for instance
    4. Control pests such as rodents, flies and stray animals

    It takes time and effort to keep up with a biosecurity program, but the benefits are substantial. Your farm and your horses will be healthier and safer for all your hard work.

    Registered 2011 Equestrian Collections; Author:  Sallie S. Hyman,  VMD, DACVIM, CVA 

    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional.  In particular, all horse owners should seek advice  and treatment from a licensed veterinarian for their horses' medical care.  

  • Thrush. What is it? How do I treat it?

    Equine Thrush or "Man Do Your Feet Stink!"

    What is Thrush?

    Thrush is caused by an anaerobic (without oxygen) bacterial infection of the frog of the foot; specifically, a moist exudative dermatitis of the central and lateral sulci (clefts) of the frog.  The most commonly cultured bacteria is Fusobacterium necrophorum.  This bacterium incites a strong tissue reaction and causes the characteristic black exudate associated with thrush.  The strong tissue reaction can be quite painful in some cases.

    Does My Horse Have Thrush?

    Now, not every horse with black discharge and smelly feet has thrush.  Horses live in unclean environments and are constantly walking through urine, manure, and mud.  These can pack into the frog and produce a foul smell and appear like black discharge.  Although the disease was once thought to be associated with these unclean conditions, this is not always the case.  Some horses live in the wettest, dirtiest conditions and never develop thrush, while others who live in the cleanest, driest stalls are plagued by thrush.

    So why the difference? 

    Some practitioners attribute it to the health of the hoof.  Good nutrition will produce a strong hoof and proper trimming/shoeing will aid in the normal self cleaning mechanism of the foot.  Veterinary podiatrist, Dr. Stephen O'Grady, describes this mechanism:

    The horse possesses a natural hoof cleaning mechanism.  in the normal foot, as weight is placed on the limb, the third phalanx (coffin bone) will descend, causing the sole to flatten.  Descent of the coffin joint occurs as the navicular bone gives in a distopalmar (downward) direction, pushing against the navicular bursa and the deep flexor tendon, and finally causes expansion of the frog as it approaches the ground surface.  This continuous change in the structure prevents the accumulation of material in the bottom of the foot.  Impairment of this hoof cleaning mechanism appears to the outstanding cause of thrush.

    Chronic lameness, improper trimming, and insufficient exercise can lead to impairment of the hoof cleaning mechanism.  When the foot is not properly cleaned, by both self mechanism, and proper grooming) manure, shavings and mud get packed into the clefts of the frog.  This traps moisture and decreases the oxygen in the area and promotes the growth of bacteria. 

    How do I treat thrush?

    Treatment must address both the bacterial infection and the underlying cause of the impairment of the self cleaning mechanism.  Topical anti-thrush medications will resolve the bacterial infection.  Proper trimming and balancing the foot will help to return it to its normal function.  Any chronic lameness should be diagnosed and treated by your veterinarian.  If your horse becomes lame from the thrush, you should contact your veterinarian for help.

    By addressing all the factors causing thrush, you will be able to treat and eliminate those stinky (and sore) feet!  

    Registered 2011 Equestrian Collections; Author:  Sallie S. Hyman,  VMD, DACVIM, CVA 

    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional.  In particular, all horse owners should seek advice  and treatment from a licensed veterinarian for their horses' medical care.  

  • Equine First Aid. What do I Need?

    Emergencies happen. Being prepared can help you get through them with less stress. Having an emergency kit in your barn and trailer is a good place to start. The kit should contain all of the basic items to get you through the most common emergencies until your veterinarian arrives, if he/she is needed.

    Keep your vet’s phone number on a laminated card in you emergency kit so that it is handy. Also keep some human emergency supplies on hand in case you don’t keep a separate human first aid kit. Your kit can be kept in a clean plastic storage box. If you don’t have a lot of room, you can even use a clean water/food bucket. Just use plastic wrap and duct tape to seal the top.

    Emergency Kit Supplies:
    Ask your veterinarian if she would like you to keep the following supplies. These must be obtained through your veterinarian.
    • Silver Sulfadiazene ointment
    • Banamine®
    • Equioxx®
    • Phenylbutazone
    • ophthalmic ointment
    Registered 2011 Equestrian Collections; Author:  Sallie S. Hyman,  VMD, DACVIM, CVA

    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional.  In particular, all horse owners should seek advice  and treatment from a licensed veterinarian for their horses' medical care.  

  • Grazing Muzzles and Metabolic Syndrome

    Does My Horse or Pony Have Metabolic Syndrome?

    We've all seen them, the horse in the field looking like Hannibal Lector in a muzzle.  It's not keeping them from biting; it's keeping him from eating!  Grazing Muzzles have become an unfortunate necessity for many horses today.  Much like people, horses are suffering from the effects of overeating and obesity.  These horses seem to get fat on air and are often called "easy keepers."  There is likely a genetic predisposition that makes these horses very efficient at utilizing calories and, in turn, makes them require a lower plane of nutrition than their naturally thinner pasture mates.

    The term Equine Metabolic Syndrome has been used to describe this condition.  The four features of the syndrome are:
    • Obesity
    • Regional adiposity (fat deposits)
    • Insulin resistance
    • Laminitis
    The results of the syndrome in horses can be devastating if not managed properly.   

    Although Equine Metabolic Syndrome can affect any breed, pony breeds seem to be overrepresented.  Horses 5-15 years of age are most commonly affected, but again, almost all age groups have been affected.  Environmental conditions certainly are part of the picture, with problems occurring when the pasture is in growth or stress phases, but genetic predisposition comes into play, as not all horses out on the same pasture will be affected. 

    Diagnosis of Equine Metabolic Syndrome is based on the clinical presentation of the horse and blood tests.  Regional adiposity is easy to recognize as the cresty neck and fat pads on the barrel and croup.  Resting insulin concentrations can be measured after the horse has been fasted for 12 hours.  This is an easy and useful test, but can be affected by pain from laminitis or if the horse eats to close to the time the blood is drawn.  Have your veterinarian examine your horse immediately if you notice lameness.  Sensitivity to foot testers at the toes of the feet and rotation of te coffin bone on radiographs are diagnostic for laminitis.  Finally, it is important in the older horse to test the ACTH levels to make sure that they don't have Cushing's disease.

    How Do I Treat Equine Metabolic Syndrome?

    Dietary Management is the most important aspect in managing horses with Equine Metabolic Syndrome.  Obese horses should be placed on diets to promote weight loss.  Most of these horses can have limited hay or pasture (hence the grazing muzzle!) and access to salt and minerals.  These horses DO NOT need grain.  They should be fed hay at 1.5-2% of their body weight (about 15-20 lbs for a 1000 lbs horse).  You should weigh your hay to make sure you are not overfeeding.  Decrease the amount of hay if your horse has access to pasture.  Ask your veterinarian if your individual horse needs any vitamin or protein supplementation based on your situation.

    What about Exercise?

    Exercise is the second ingredient to managing Equine Metabolic Syndrome.  Obviously, laminitic horses should not exercised until their pain is gone, the rotation of the coffin bone is corrected, and the inflammation of the foot is stabilized.  Non-laminitic horses should receive daily exercise to promote weight loss.  Just like with people, the only way to lose weight is to burn more calories than you consume.  There is only so far we can restrict calories, so that means we must exercise our horses.  This can include walking on a lead, lunging or riding.  Any type of exercise is better than none!

    How about Medications?

    Some medications can be used to help with weight loss such as levothyroxine sodium or meformin.  These are used in individual cases and can be discussed with your veterinarian. the grass continues to grow, watch your horse's weight.  Consider a grazing muzzle if he is gaining weight and is on pasture.  Consult with your veterinarian if you have questions as to whether or not your horse might have Equine Metabolic Syndrome or insulin resistance. 

    Registered 2011 Equestrian Collections; Author:  Sallie S. Hyman,  VMD, DACVIM, CVA  

    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional.  In particular, all horse owners should seek advice  and treatment from a licensed veterinarian for their horses' medical care.         



  • Shoo Fly! Horses vs. Flies ...

    Shoo Fly!

    Summer time brings warm weather, longer days, and FLIES.  Just when we are happy to spend more time with our horses, the flies and gnats come to ruin our good time!

    Are flies really a serious issue?

    While people find their buzzing to be a nuisance, flies and gnats can cause several medical problems in our horses.  Not only are fly and gnat bites very irritating to horses, just like people some horses are more sensitive to them than other horses.  Further, flies can cause disease directly, mostly due to their bite, or by spreading disease that they are carrying.  Flies are excellent vectors for many diseases.

    What irritations are associated with flies?

    Sweet Itch:  Culicoides hypersensitivity, commonly called Sweet Itch or Queensland Itch, is cause by the bite of the culicoides midge (no-see-ums!).  Horses develop an allergy to the saliva of the culicoides midge.  The mane, tail, and ventral midline areas of the horse are most commonly affected.  Horses develop severe pruritis (itching) and will often create further skin damage with excessive rubbing. 

    Deer Fly Hypersensitivity:  Deer fly hypersensitivity has also been seen in horses.  The allergens in the deer fly bite can cause severe hives to develop.

    Eye Irritation: Eye irritation is very commonly seen during fly season.  Flies feed off of tears and bite the conjunctiva of the eye in the process.  Inflammation can develop that can eventually lead to blockage of the nasolacrimal duct and result in excessive tearing.  This, of course, leads to more feeding by flies.  Should you suspect a blocked tear duct in your horse, contact your veterinarian.  Your vet will examine your horse to make sure there is nothing else wrong with the eye and flush the nasolacrimal duct to open it up.  You may also be given some eye drops or ointment with antibiotics and steroids to help with the inflammation.  It is important for your veterinarian to examine and stain the eye before starting any eye treatment with steroids to make sure that there are no ulcers on the eye.

    Corneal Ulcers: Corneal ulcers are common during fly season.  As horses try to rub away flies, they may accidentally scratch the corneal surface on fences or trees.  Any problem with the eye that includes tearing, cloudiness, holding the eye partially or fully shut, or swollen lids should be treated as an emergency.  Call your veterinarian to examine it. It is very important to get your horse on the correct medicine in order to treat possible bacterial and fungal infections.  Without correct treatment a simple ulcer can turn into a major problem.  As mentioned above, never use steroids in an ulcerated eye.  

    What about Diseases?
    In addition to irritations, flies also carry and transmit a host of diseases.  They can carry viruses, bacteria, and parasites. 

    Sarcoids:  Sarcoids are one of the most common skin tumors in the horse.  They can be flat roughened areas or protruding cauliflower like masses.  They are thought to be caused by a retrovirus or a papilloma virus.  Flies are suspected to be able to transfer the sarcoid cells from one horse to another by depositing them in traumatic skin wounds. 

    Ear Papillomas:  Ear papillomas are virally induced skin tumors that appears as warts in the ear.  They are transmitted by black flies.

    Summer Sores:  Habronemiasis, or summer sores, is casued by nemotode larve. Habronemia musca and Draschia microstoma are the species that affect horses.  The adults live in the horse's stomach.  The larvae are passed out into the feces where they are eaten by fly maggots.  The larvae stay within the developing fly and are then deposited on the lips, eyes, or wounds of the horse as the flies feed.  If the larvae are digested, they will develop into worms in the horse's stomach. However, if they are deposited in the eyes or traumatized skin, the larvae cannot develop and instead incite an inflammatory reaction.  The larvae become walled off in granulation tissue and a non-healing pink tissue mass ensues.  Yellow granules can be found within the mass.  These are dead and dying larvae.  As the flies like to feed in moist areas, Habronema lesions are commonly found on the lips, third eyelid, and penis.  The lesions are quite itchy, and the horse may cause secondary trauma from rubbing.

    Pigeon Fever:  Pigeon fever, caused by the corynebacteria pseudotuberculosis, is also carried by flies.  The flies introduce the bacteria into the skin and underlying tissues.  it is then carried by the bloodstream to deeper tissues and lymph nodes.  Abscesses characterize the disease.  They are most commonly found in the pectoral (chest) region, causing the chest to look as if it is protruding, much like a pigeon's breast.  Your veterinarian should be consulted if you suspect your horse has pigeon fever.

    Rain Rot:  Dermatophilosis, or rain rot, can be spread by flies although it is more likely to be transmitted from horse to horse by shared tack, brushes, and blankets.  This bacterial infection, caused by dermatophilous congolensis, results from the bacteria being introduced to moist, injured skin.  The matted, crusty scabs that lift off easily to reveal moist lesions underneath are unmistakable.  Your veterinarian should be consulted if you suspect your horse has rain rot. 

    You've convinced me!  Flies are a serious problem.  Now what do I do about it?!

    The key to avoiding the myriad of fly vector diseases is to try to keep flies from reaching your horse.   Fly sheets and fly leg wraps will keep the majority of flies from reaching your horse.  Use fly repellents as an additional weapon.  Fly masks will keep the flies from irritating your horse's eyes.  Fans are a good way to help keep culicoides away.  They are dawn and dusk feeders.  If you can keep your horse in a stall with a fan at those times, you can literally blow the no-see-ums away.  Culicoides are not strong fliers.

    Be sure to check your horse carefully everyday to look for any signs of skin or eye problems that flies might bring.

  • Equine Vital Signs. What's Normal?

    Vital Signs

    Every horse owner should now what the normal temperature, heart rate, and respiratory rate (TPR) for their horse and know how to obtain these numbers. In addition, you should also know some other basic "normal" such as borborygmi (gut sounds), mucus membrane color, and capillary refill time.  Knowing what is normal will help you when things aren't so normal.  This is important and useful information that you can convey to your veterinarian if you suspect your horse is having a problem. 

    Temperature (T)

    A horse's normal body temperature ranges from 99-101° F.  Your horse's normal body temperature can vary up to three degrees depending on environmental factors such as the weather, stress, and exercise.  It will be higher in warmer weather, if he is excited, if he has just exercised, and often times, in the early evening.  You should take your horse's temperature at different times of the day to get a baseline for what is normal for your horse.

    How to take your horse's temperature: 
    Currently, the most accurate way of taking a horse's temperature is rectally.  Today's plastic digital thermometers have made this much quicker and easier.  No matter what type of thermometer you use, digital or mercury, it is a good idea to tie a string with a clip onto it in order to keep from losing it if it should drop on the stall or, heaven forbid, get sucked in.  Lubricate the thermometer with Vaseline, KY jelly, or spit.  Stand next to your horse, not directly behind him, and gently insert the thermometer into the rectum.  Wait for a digital thermometer to beep or 2-3 minutes for a mercury one.  Clean your thermometer thoroughly with soap and water or alcohol after each use to prevent spreading disease.

    Any temperature about 102° F or higher should prompt a call to your veterinarian.  A fever does not always indicate an infection, but any condition that increases normal body temperature should be looked at. 

    Heart Rate (HR)

    The normal heart rate of an adult horse at rest is 30-40 beats per minute (bpm).  Foals have a higher resting heart rate that averages 70-120 bpm. Your horse's heart rate will be higher if he is excited, in pain, has certain diseases, or has just exercised.

    How to take your horse's heart rate:
    To take your horse's heart rate you can either use a stehoscope to listen to his heart or feel his pulse on his facial artery or digital artery.  These tow arteries are easy to find for most people.  The facial artery runs along the outside of the bottom of his jawbone.  The digital artery runs on the outside of his leg at the level of his fetlock.  Press down gently over the artery to feel the pulse.  to use a stethoscope, place it on your horse's chest just behind the elbow.  You can count the number of beats in fifteen seconds and multiply by four.

    Heart rates no associated with exercise, especially if combined with abnormal behavior should be taken seriously.  Any heart rate over 40 bpm warrants a call to your veterinarian.  A heart rate over 60 bpm indicates a severe condition and should be treated as an emergency.  

    Respiratory Rate (RR)

    A normal respiratory rate for an adult horse is 8-15 breaths per minute (bpm).  Respiration should consist of inhalation and exhalation, which should be of equal length.  Heat, humidity, exercise, fever, and pain can cause increase in the respiratory rate.

    How to take your horse's respiration rate: 
    Watch as your horse's chest moves in and out, or place your hand on his chest to feel it move in and out.  You can also use your stethoscope to listen to the breaths either on his lungs or on his trachea.  Again, count the number of breaths for fifteen seconds, and multiply by four.

    A high respiratory rate, increased effort when inhaling or exhaling, or noise when breathing should prompt a call to your veterinarian.

    Borborygmi (Gut Sounds)

    Horse's intestines are in almost constant motion and that results in constant noise from them.  Sometimes the sounds may be quieter than others, but they are always there.  Excessive sounds may indicate irritation or inflammation of the intestines, as in the case of diarrhea.  The absence of borborymi can indicate a serious problem, such as colic.

    How to listen for Gut Sounds:
    You can place your stethoscope on either side of your horse's flank and listen for gurgling, gassy, and "fluidy" sounds.  You should be able to hear these on both sides.  You can also place your ear to your horse's flank and listen if you don't have a stethoscope.  Most horse's have load enough gut sounds that you can hear them even without a stethoscope.

    If your horse has no borborygmi and any other signs such as loss of appetite, fever, pawing, or laying down, contact your veterinarian.  

    Capillary Refill Time (CRT)

    Capillary Refill Time (CRT) is the time it takes for blood to return to blanched tissues in the gums.  This is an indicator of blood circulation.  Normal refill time is one to two seconds.

    How to check your horse's capillary refill:
    To check your horse's CRT, lift his upper lip and press on his gums.  Count how long it takes for the normal pink to come back to the area you pressed.

    If your horse's CRT is three seconds or more it can indicate poor circulation, dehydration, or illness.  Contact your veterinarian.  

    Mucus Membrane Color

    Mucus membranes are th tissues that line the eyelids, lips, gums, nostrils, and vulva.  The color of the mucus membranes is another indicator of blood circulation.  Healthy mucus membranes are a moist pink.  They can sometimes have a pale yellow tinge to them as well.  Dry mucus membranes may signal dehydration.

    Color can indicate various conditions:
    • Very pale pink:  blood loss, anemia
    • White: severe blood loss anemia, shock
    • Bright red/red purple: toxicity, mild shock
    • Gray/Blue: severe shock, decreased oxygen
    • Bright yellow:  Liver disease

    If your horse's mucus membranes are any of the above, contact your veterinarian immediately

    Knowing what is normal for your horse will help you determine when thing are NOT normal, and provide a wealth of information for your veterinarian. 

    Registered 2011 Equestrian Collections; Author:  Sallie S. Hyman,  VMD, DACVIM, CVA  

    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional.  In particular, all horse owners should seek advice from a veterinarian for their horses medical needs. 

  • Sheath and Udder Cleaning

    Sheath and Udder Cleaning

    Any one who owns a gelding or a stall ion should be aware that they have some special hygiene requirements.  The equine penis secretes smegma to clean and lubricate the penis.  The origin of the secretions is still disputed.  However, it is know that smegma is composed of exfoliated skin cells, oils, and moisture.  The equine penis, when retracted is contained with the sheath.  Therefore, the inside of the sheath will also become coated with smegma.  A feature unique to the equine penis is the urethral diverticulum and fossa.  This cleft like area around the urethral opening becomes an ideal location for smegma to accumulate.  This accumulation is often referred to as a"bean" due to its oval shape.

    So if Smegma is naturally occurring, why do we have to clean it?!

    Some horses produce large amounts of smegma.  Over time, the accumulation can begin to coat the sheath and ventral abdomen, making the hair gummy.  This can become a minor grooming annoyance.  More significantly, the smegma can take on an extremely unpleasant odor.  It is one of those smells that once you have experienced it, you never forget it! Most significantly, an over-accumulation of smegma in the urethral diverticulum can put pressure on the urethra, causing pain or obstructing the flow of urine.  Some horses will manifest their discomfort by rubbing their tails, trying to scratch their sheath on whatever is convenient, such as shrubs and fences, not dropping their penis to urinate, or straining to urinate.

    How often should I clean my horse's sheath?

    How often you clean your horse's sheath and penis will depend on how much smegma he produces.  Just as not cleaning your horse's sheath can result in problems, so, too, can cleaning it too much.  The penis has beneficial bacteria on its surface.  The skin in this area is also very thin and sensitive.  If you clean it too often or with harsh cleaners you can kill off the good bacteria or cause the skin to become dried out, inflamed, or cracked.  This will allow bad bacteria to flourish and cause a skin infection.

     Most horses should have a thorough sheath cleaning every 6-12 months. A thorough cleaning will also allow you to examine the sheath and penis for any signs of neoplasia such as sarcoids, melanomas, and squamous cell carcinoma, habronemiasis or infections.

    Ok, I need to clean his sheath.  How do I go about doing it?

    The cleaning process can be a challenge in some horse.  Many find the whole experience quite unpleasant (as do many horse owners!).  If your horse is upset by the procedure, it is best to have your veterinarian come out to sedate him.  This will relax him and make him drop his penis out of the sheath.  It will then be easier to clean the entire penis and check for a bean.  Only mild products should be used for cleaning.  Ivory Soap has been a staple for many years.  More recently sheath cleaning products containing gentle ingredients such as mineral oil have become available that help to soften the smegma to facilitate its removal.  Plenty of warm water should be used to rinse away any soap or product you use.  Avoid using betadine or chlorhexadine products unless directed by your veterinarian, as they are too harsh for routine cleaning. 

    So none of this applies to the mares, right?!

    Wrong!  Let's not forget the mares when it comes to cleaning those personal parts.  Although mares don't product smegma in between their teats, they do accumulate dirt, sweat, and dead cells there.  This accumulation can become flaky, itchy, and a place for bad bacteria to fester.  Mares will often cause self-trauma trying to scratch their udder on shrubs or fences, much like their male counterparts.  you can use the same products on mares to soften and remove the debris between their teats.  Use the same caution in approaching the procedure as you would with cleaning a gelding or stallion's sheath.  Some mares are very sensitive and will not tolerate the procedure.  Call your veterinarian to come sedate her.  Safety for all is priority number one.

    Registered 2011 Equestrian Collections; Author:  Sallie S. Hyman,  VMD, DACVIM, CVA  

    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional.  In particular, all horse owners should seek advice  and treatment from a licensed veterinarian for their horses' medical care.  




  • Cribbing. How Do I Make it Stop?


    What Is It and How Do I Make Him Stop?

    "Does he crib?"  It's as common as asking what color a horse is when you are looking to purchase one.  Most people try to avoid bringing a new cribber into their barns.  Those who own a horse that cribs are usually frustrated at the the habit and are trying to stop it.

    What exactly is cribbing?

    Cribbing is a stereotypy, that is, a behavior that is repetitive and compulsive.  The behavior includes the horse grabbing onto something solid (like a fence board, bucket, or door) with his top incisors, arches his neck, and sucks in air.   An audible gulping or belching can usually be heard.  Some horse can crib without their teeth on anything.  This sucking in of air causes a kind of "head rush" for the horse.  The head rush is pleasurable.  Cribbing should not be confused with wood chewing.  Although a cribber may damage the surface he cribs on due to scraping his teeth over it repetitively, he is not biting and chewing wood.

    So why do horses crib?

    Animal welfare researchers believe that this stereotypy may serve a purpose in relieving stress or physical discomfort.  Some reasons commonly attributed to cribbing include:
    1. Boredom
    2. Stress
    3. Nervousness
    4. Excessive energy
    5. Nutritional deficiencies

    Researches are still divided on whether or not a horse that cribs can teach other horses to crib.  Dr. Sue MacDonnell, from the University of Pennsylvania, has studied cribbers for many years.  It is her experience that it is very rare for a cribber to teach other horses the habit.  Rather, horses in the same vicinity who all share the cribbing habit, are most likely exposed to the same stressors.  Since horses have limited ways in which to show their stress, they each choose to crib.  They have chosen this independent of one another, not learned from one another.   

    Is cribbing unhealthy?

    Cribbing can have undesirable health effects on your horse.  Many horses will wear down their top incisors, sometimes right to the gum line.  This will make prehending food difficult for the horse.  It can also result in a malocclusion of the teeth of the upper and lower jaws.  Special attention should be paid to the teeth of a cribber to prevent any problems associated with tooth wear.

     Studies show that there is also a higher association with colic in horses that crib.  No certain type or severity of colic, but just an increased risk.  It was once thought that cribbers got more gas colic, but studies have not found that to be true. 

    Some horses can become so addicted to the rush of cribbing that they will forsake eating for it.  This can result in a weight loss, malnutrition, and poor performance.

    So how do I prevent cribbing? 

    The best way to help prevent a horse from starting to crib is to try to eliminate or at least lessen the stress and boredom in his life.  Allow your horse as much pasture time as possible in your given situation.  Horses are social animals, so contact with other horses will help decrease stress.  A goat or chicken can provide social interaction for some when other horses are just not available.  Regular exercise to eliminate excessive energy and provide stimulation is also important. 

    Changing your horses diet can be helpful.  It is recommended to decrease or eliminate grain from a a cribber's diet.  Providing roughage throughout the day is important.  Eliminating grain is hard for those horses who are underweight, but it may relieve the behavior.  Researchers in the United Kingdom are working with special diets for cribbers that contain antacids, meant to reduce cribbing in established cribbers. 

    Another way to reduce cribbing is to make the surfaces your horse cribs on less desirable.  Cover tops of door with rounded metal edges or paint boards and doors with anti-chew spray or cayenne pepper.

    What about cribbing collars ?

    Cribbing collars can be an effective means of controlling cribbing in some horses.  It is often necessary to try several different styles to get one that works for your horse.  And it is often necessary for the collar to be very tight.  Monitor your horse for any signs of abrasions from the collar as well as any difficulties breathing.  There have been some instances of horse who pass out from wearing a very tight cribbing collar.  However, these cases are rare and controlling the behavior is very important.

    Other control methods such as shock collars, acupuncture, and surgery are available. None of these methods have been found to be particularly effective. 

    Cribbing can never be cured, but with some modifications to your horse's lifestyle, it can be managed.   

    Registered 2011 Equestrian Collections; Author:  Sallie S. Hyman,  VMD, DACVIM, CVA         

    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional.  In particular, all horse owners should seek advice  and treatment from a licensed veterinarian for their horses' medical care.       

  • Saddle Pads. What Kind Should I Buy?

    Saddle Pads:  Which Should I Choose?

    A look through the choices of saddle pads can leave you with your head spinning.  Open cell, closed cell, foam, gel, cotton, sheepskin, the varieties are endless.  So what makes a good saddle pad and which one should you choose?

    Why do we use saddle pads at all?

    The primary purpose of a saddle pad is to provide comfort for the horse when he is ridden.  It acts as a buffer between the hard saddle and the skin and muscles of your horse's back.  Saddle pads also act to wick moisture and heat from the surface of the skin.  this can help prevent slipping of the saddle and potentially manage muscle fatigue due to heat.    And of course, a saddle pad helps to keep sweat and dirt off o your very expensive saddle!

    What about saddle fit?

    A pad can help correct minor saddle fitting problems by filling in spaces where the saddle doesn't contact properly, but a saddle pad should never be a substitute for proper saddle fit.  Many studies have been conducted to assess saddle fit.  These have shown that pressure areas or patterns from the saddle increase in severity with increases in speed, weight, and instability of the rider, or ill fit of the saddle.    A saddle pad should ideally help to alleviate pressure areas, or at least not make then worse. 

    What about all the different materials?  What is best for my horse?

     A recent study by Kotschwar, et al. out of the Movement Science Group Vienna, clinical Department for Companion Animals and Horses, University of Veterinary Medicine, Austria, independently evaluated different types of saddle pads.  In their study, horses were ridden at the walk and sitting trot on a treadmill while wearing a dressage saddle and four different saddle pads.  Additionally, they were tested with no saddle pad as a control.  The four types of saddle pads were gel, leather, foam, and reindeer fur. Yes, reindeer fur!  They used a pressure pad under each of the saddle pads, as well as the saddle alone, to collect data on pressure distribution.  They also collected data on what they called maximum overall force (MOF).  A decrease in MOF indicated improved saddle fit, whereas an increase in MOF indicated worsened saddle fit.  Only the reindeer  fur pad decreased the MOF and the pressure distribution!  None of the other pad worsened any of the pressure measurements. 

    Another study looking a different types of Western saddle pads found that none of them did any harm, but none were significantly better than others.  It did find that more expensive pads tend to hold up better. (They tested each pad for 200 hours of riding).

    What does all this mean?!

    Unless you can get your hands on a reindeer fur saddle pad, the studies suggest that most of the popular styles available today will do the job.  Which one you chose can be based on your budge, amount of use it will get, fashion sense and ease of care. 

     Registered 2011 Equestrian Collections; Author:  Sallie S. Hyman,  VMD, DACVIM, CVA    

    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional.  In particular, all horse owners should seek advice  and treatment from a licensed veterinarian for their horses' medical care.  

  • Trailering 101

    Trailering 101

    It seems like many horses today should have their own frequent mileage cards, given the amount of traveling they do.  We take them to lessons, competitions, trail rides,and sometimes even on vacation.  All of that trailering can take its toll on them, however. So how do we keep our equine companions happy and healthy during our travels?

    There are a plethora of studies out there documenting the effects of long distance travel on the equine immune, respiratory, and musculoskeletal systems.

    Immune System:

    Trailering causes stress that has affects at the physiological level.  Cortisol, a stress hormone, increases from the start of trailering through the entire trip.  It then takes 11-36 hours of rest for it to return to baseline levels.  Cortisol decreases immune function and affects glucose metabolism. The white blood cell counts increase in neutrophils, decrease in lymphocites, resulting in an an increase in the neutrophil:lymphocyte ratio.  This suppression of the immune system can leave horses susceptible to viruses that are common in co-mingling populations of horses such as influenza and rhinopheumonitis.  Horses recovered from Equine Protozoal Myelitits (EPM) are more likely to have a recurrence of the disease after long distance trailering due to this immune system suppression.

    Equine Respiratory Disease and Trailering:

    Tying a horse's head in a trailer has been shown to increase the chance of respiratory disease.  Think of all the airborne particulates flying around the trailer at 75 mph as you are trucking down the roads.  Your horse is breathing in all of these.  Horses clear debris and bacteria from their trachea in two ways.  One is simple gravity.  Your horse puts his head down to graze and gravity pulls the debris from the trachea out through the nostrils.  The other method is mucocilliary transport.  thousands of tiny finger-like projections transport bacteria and debris from deep within the trachea and out of the respiratory system.  Both of the these methods are impaired when your horse's head is tied to chest level. 

    In fact, it takes just 6-8 hours for significant numbers of bacteria to accumulate in the lungs with the head tied.  This, combined with impaired immune function, can result in bacterial pleuroneumonia (infection of the lungs and lung cavity), also known as Shipping Fever.  Symptoms of shipping fever include:  loss of appetite; fever (usually higher than 102° F); increased respiratory rate; shallow breathing (due to pain in the chest cavity); cough (which they may try to suppress due to pain); and sometimes nasal discharge.  Shipping fever is a very serious condition and can be fatal, or can lead to severe or fatal complications such as colic and laminitis.  

    Musculoskeletal Systems and Trailering:

    While we sit in the comfort of our truck towing our horses, what is their comfort level?  Being on a trailer is, in actuality, the equivalent of walking for a horse.  They are constantly shifting their weight and moving their feet to stay balanced.  Just keep in mind that an eight hour trailer ride for your horse is like going for an eight hour walk.  Blood tests done after trailering show increased muscle enzymes similar  to those in exercising horses.  If you are trailering a very long distance it is wise to take one hour breaks every six to eight hours to allow your horse to rest.  If this is not possible, then allow adequate rest, usually twenty-four hours, upon arrival. 

    Dehydration and Weight Loss:

    Studies have shown that horses do not eat or drink as well when traveling, sometimes becoming up to 4% dehydrated.  That degree of dehydration takes a while to be corrected through voluntary water consumption.  Horses who do not eat well can lose weight and certainly not be at the top of their performance.  Resist the urge to overdo the electrolytes during travel. Too much can exacerbate the dehydration if your horse is not consuming enough water.  (Think about eating a bag of potato chips without a drink!) And while we want our horses to have something to eat and to occupy their time while we are driving, think twice too, about the hay you put in front of them.  There are billions of dust, mold, and bacteria in that hay, not to mention larger particles that can be inhaled or get into their eyes.  The best way to feed and water your horse on long journeys is to stop briefly every four hours.  Allow your horse to be untied so he can lower his head, then feed and water your horse from the ground.  This allows him to clear his trachea and to eat in a more normal position. 

    How to Travel Safely:

    We need to be able to travel with our horses, but we also need to do it in a manner that keeps them as comfortable and healthy as possible. 

    Before you go:

    Take your horses vital signs before you get going so you will know what is normal for him.  Don't exercise excessively the day before travel.  We know that maximal exercise can decrease immune function, so it is best not to start out already suppressed and tired, to boot. Give your horse plenty of hay the night before and decrease his grain meal if he gets one.  Encourage him to drink plenty of water.  Use water flavoring, like some of the horse teas, Gatorade or anything that gets your horse to drink.  Make sure that your trailer has good ventilation.  This doesn't mean letting your horse stick his head out of the window like a dog (which I have seen!), but having proper venting and window screens to let in the fresh air and to keep out any road debris.  IF you don't have window screens consider having your horse wear a fly mask when traveling to help protect his eyes.  If you are driving in hot weather, try to drive at night when the temperatures won't be so high.  Also, two mats on the floor will keep your horse from being so near to the heat from the floor.  A safety thermometer in the trailer will let you see what temperature your horse is contending with in the trailer.   High temperatures won't necessarily make you scrap your plans to travel, but it will let you know whether or not you should take more water breaks.  And, finally, make sure your truck and trailer are in good running order before you ever hit the road! 

    When you arrive: 

    Once you reach your destination, make sure your horse gets plenty of rest, fresh water, and hay.  He can have his normal grain meal as well.  Check his temperature twice a day for the first three days at your destination to make sure that he hasn't developed shipping fever.  Try to arrive at least twenty-four hours before your competition in order to allow him to recover fully from the stress of the trip.  If you have any concerns about your horse's health when you arrive, contact a veterinarian.

  • Saddle Fitting

    Saddle Fitting

    It has been said that a correctly fitting saddle is as important to an equine athlete as correctly fitting shoes are to a human athlete.  In fact, proper saddle fitting is important for both horse and rider.   The saddle on our horse's back is our connection to him when we are riding.  Anatomically, that region consists of the skin, with thousands of nerve endings, the epaxial muscles, the spinal vertebrae, and the junction of the ribs and vertebrae.

    What are the signs of poor saddle fit? 

    If a saddle does not fit a horse properly, pain, performance issues and behavior problems can result.  Signs of saddle fitting problems include, but are not limited to: obvious sores; white hairs under the saddle; swelling under the saddle; sensitivity to palpation or grooming of the saddle area; "cold backed;" resistance to work; tail swishing; not traveling straight;  general bad attitude; difficulty with collection; and many other subtle performance issues. 

    How do I know if it is a tack problem or a medical problem?

    If your horse show signs of bucking, inability to keep on a canter lead, bunny hopping at the canter, twisting over fences, or is very difficult to collect, these may be signs of mores substantial back pain with true musculoskeletal changes such as kissing spine (dorsal spinous process impingement) or vertebral osteoarthritis.  Any horse exhibiting signs of back pain should have a thorough evaluation by a veterinarian including radiographs of the back to rule out orthopedic causes of back pain.  In no boney changes are present, then saddle fit should be evaluated.

    So how do I check saddle fit?

    There are many resources available to learn about saddle fit, as well as many qualified individuals who can help you evaluate your horse for proper saddle fit.  [Note from Equestrian Collections - You can check on-line for Master Saddle Fitters in your area] The magnitude of information needed to correctly fit a saddle is beyond the scope of one article, but there are some major points which all equestrians should be aware of.


    Examine all saddles carefully for any structural defects or asymmetry.  Twisted trees or asymmetric panels will cause pressure points on your horse's back.


    This is the most critical aspect of saddle fit.  Most riders tend to place the saddle too far forward, covering the scapula.  [Place the saddle slightly forward on the horse's withers.  Press down on the pommel and slide the saddle rearward until it stops at the resting place dictated by the horse's confirmation, well behind the shoulder blade - Master Saddlers Assoc.] 

    Panel and Bars:

    The panels are the underside of the saddle that contacts the horse's back.  If the saddle is placed too far forward, the panels will contact the back only in front and in back and "float" in the middle.  This will create pressure on these contact points.  The angle of the panels should allow even contact along the back.  The gullet of the saddle is designed to keep pressure off the horse's spine and should span either side of the spine by 1-2 inches.  No part of the saddle should directly contact the spine.  

    A Western saddle has bars.  The bars need to have enough curve and flairs so that it fits the contours of the horse's back.


    The tree is the internal structure of the saddle.  Traditionally, trees are wood, but they can be made of many new high tech materials now.  They can also be fixed or adjustable. The tree crosses over the withers, and should not put ANY pressure on the withers.  It should fit without a pad underneath it.


    The seat of the saddle should be level as viewed from the side.

    Rider Fit:

    Remember, the saddle needs to fit the rider as well!  If the fit is not proper for the rider, then improper balance can result.  This will result in the rider causing pressure points on the horse's back.  Additionally, the rider may experience pain from trying to compensate for poor balance or being in an unnatural position. 

    So once we get a good fit, we're set?

    No!  Just when we think we have the right fitting saddle, horses go and do something sneaky.  Their bodies change.  As we work them and they develop more muscle and lose fat, that perfectly fitting saddle may no longer fit so well.  It is important to re-evaluate your saddle fit as your horse develops throughout the year.  This may require that you have your saddle reflocked, or maybe even a new saddle.  These are, however, small investments to ensure that your horse can give you his best performance.     

    What's next in saddle fit and technology?

    There are computerized methods to determine saddle fit.  A computerized saddle pad is placed under the saddle and pressure measurements are made while the horse is worked at the walk and trot, on the lunge and while ridden.  Another method is to use thermography on both your horse's back and saddle to see if there are any areas of uneven temperature (indicating lack of contact or pressure points) while riding.  These can be used as adjuncts to visual inspection of fit and measurements of your horse.


  • To Blanket or Not to Blanket

    To Blanket or Not to Blanket ...

    Winter is here!  The days are short, and the nights are long and cold in much of the country. As we manage our horses in the colder weather, the question arises of whether or not to blanket your horse.  The short answer is "no," but let's look at why that is, and under what circumstances blanketing may be preferred or necessary.

    How a horse stays warm:

    Horses have developed very efficient means of staying warm, even in very cold temperatures.  Your horse's coat is comprised of two types of hair: longer stiffer guard hairs; and a soft, fluffy undercoat.  The guard hairs "guard" or protect the soft hairs from dirt and water, shed off rain, and collect moisture from sweat that might damage the undercoat.  The softer, fluffier hairs of the undercoat trap warm air between and act like insulation around your horse. Natural oils are produced that coat the hair to make them water resistant.  Each hair is connected to the piloerector muscle.  This muscle allows the hairs to be stood up or laid flat.  When they stand up, warm air trapped between them, just above the surface of the skin.  When they lie down, warm air is released from between them, cooling the area above the surface of the skin. 

    How much winter hair will my horse get?

    Horses will start to grow their heavy winter coast sometime in late August in most parts of the United States.  The hair growth is actually linked to the length of daylight, not the temperature.  How thick their coat will grow does depend some on where you live.  A horse in Florida will not grow nearly as heavy a coat as a horse in Minnesota does, but they all grow a thicker coat for winter.

    What role does nutrition play?

    Besides the hair coat, given the right nutrition, horses will start to put on a layer of fat in late summer and early fall in preparation for colder weather to come.  Nutrition also plays a role during the cold weather.  It is important that your horse gets enough hay to eat.  The fermentation of hay in the horse's hindgut produces an incredible amount of heat.  Basically, your horse has a built in furnace that is fueled by hay.  And that sudden burst of crazy running around the pasture?  While it may seem that your horse or horses have just been spooked, or have gone nuts, this moving around is another way to generate heat.   

    How much cold can a horse tolerate?

    A Canadian study found that horses can tolerate temperatures down to 5°F before they show any drop in body temperature.  However, certain conditions do change your horse's ability to keep warm.  Rain and wind are the two most important.  Rain will flatten the hair coat and prevent the undercoat from providing that layer of warm air.  Wind will blow the warm air from the surface of the skin.  Snow is less of a problem.  In fact, snow will collect on your horse's coat and act as a layer of insulation. 

    When don't I need to blanket my horse?

    • When he has a natural winter coat
    • When he is healthy and in good body weight
    • When it is not too windy or raining
    • If the temperature says above 5°F  

    When do I need to blanket my horse?

    • When he has been clipped for winter
    • When he is sick or injured
    • When he is underweight  (or any "hard keeper")
    • When he is older, with weight issues, or difficulty moving around
    • When he has been recently moved to a colder climate (Expect it to take 10-21 days for a horse to acclimate to a new climate)
    • When it is Windy or Rainy or both
    • When there is no available shelter  

    Here are some general guidelines:

    • Body Clipped Horses:  Start blanketing when the temperature gets below 60°F, or anytime it is rainy or windy
    • Moderate Hair Coat Horses:  Start blanketing when the temperature goes below 40°F 
    • Heavy Hair Coat Horses:  Start blanketing when the temperatures go below 30°F 
    Do keep in mind, however, that most horses with a natural hair coat will do fine without blankets as long as there is no wind or rain.


    It is very important to keep in mind that there are times when blanketing is worse than not blanketing.  A blanket will make your horse's hair coat lie flat, thus removing that insulating layer of warm air.  If  the amount of insulation in the blanket is less than what your horse's natural coat would provide, then he will be cold.  Make sure that any blankets used for turnout are waterproof!  A wet blanket will make your horse cold.  Too many blankets, or too heavy a blanket will make your horse sweat, make the hairs lie down, and make your horse cold.  Stick your hand under your horse's blankets to make sure he is not too hot. Additionally, you should not see sweat marks on your horse when you take the blanket off.  

    How to blanket properly:

    Proper fit is essential to keep your horse warm and safe.  Make sure that the blanket is not putting pressure on your horse's withers, chest, or shoulders.  You may have to try several styles of blanket to find the one that fits your horse correctly.   Many horses, especially those that are clipped, will develop rub marks on the shoulders.  Slick undergarments are available to help with this. Spraying the inside of the blanket with a silicone grooming spray can also help. 

    Remove your horse's blanket often to make sure that any rubs have not turned into sores or that he hasn't developed rain rot under his blanket. 

    Make sure to use turnout blankets when horses are turned out!  These blankets are designed to stay in place when your horse runs and rolls; they are waterproof; and they are generally of studier materials to withstand herd turnout.   Stable blankets are not waterproof, plus your horse can get tangled up in a blanket that is not intended for turnout.  

    A blanket that is too small can cause pressure sores and not provide enough warmth.  Likewise, a blanket is too large can be dangerous from being too loose, as well as allow too much cold air to flow underneath it.


    Registered 2011 Equestrian Collections; Author: Sallie S. Hyman, VMD, DACVIM, CVA

    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional. In particular, all horse owners should seek advice from a veterinarian for their horses medical needs.

  • Equine Vaccination Basics

    Equine Vaccinations


    Time for Fall shots. As horse owners you diligently make an appointment with the vet to come out to vaccinate your horses as scheduled. Vaccination is an immensely important part of maintaining your horse’s health. The advent of vaccination has decreased the mortality and morbidity of many diseases that used to claim thousands of equine lives. And although every horse should be vaccinated, a one size fits all vaccination program is no longer warranted. What your horse receives should be based on sound medical advice from your veterinarian.

    Exactly what is a vaccine and how does it work?

    The word "vaccine" is derived from the Latin, vaccinus, which means "of a cow."  Edward Jenner produced the vaccine against small pox by using cow pox virus, hence the use of the term.

    When the body encounters a foreign substance, called an antigen, the immune system goes on alert.  White blood cells called T and B lymphoctes produce antibodies.  These antibodies will interact with specific antigens and form an antigen/antibody complex.  Other cells of the immune system then target these complexes for destruction and remove them from the body, thus preventing disease.  When we vaccinate, we are introducing antigen into the body in order to stimulate the body to produce antibodies against whatever disease for which we want protection.  Vaccines do not produce a large scale antibody response that might make us or a horse feel sick, but just enough to get the right antibodies.  The most important part of the immune response that takes place, however, is the development of the memory cells for that particular antigen.  If the body ever encounters that antigen again, it will mount a swift and exuberant response because of those memory cells.  This quick response will help to prevent or lessen the severity of the disease encountered.


    What different types of vaccines are there? 

    There are now several types of vaccines on the market that are designed to stimulate the immune response. Each has it pros and cons, so it is important to discuss with your veterinarian which type is best for your horse. The most widely used types used today are:     

                Modified Live- made from the disease causing agent that has been made less virulent. The agent can replicate and shedding of active agent is a small concern.

                Killed-made from the killed agent. The agent cannot replicate or be transmitted. Adjuvants (components that amplify and modulate the immune response) are necessary to make the vaccine work. Adjuvants have been implicated in some vaccine reactions.

                Recombinant-made from antigenic pieces of a pathogen that is combined into a harmless carrier.

    How effective are vaccines?

    It must be remembered that vaccination is not 100% protective. It is one part of an overall health management program. When considering vaccination, keep in mind the risk of exposure, the age of your horse, what your horse does for a living, and your geographical area. All of these factors will influence which vaccines you give and how you give them. Individuals also have different responses to vaccination as to how robust an immune response they will have or how long it will last. And no vaccine will be effective if it is not given properly. Make sure that you allow your veterinarian to give the proper initial series and boosters for all vaccines. Vaccine schedules for foals have been modified in the last few years based on research. Of greatest note is for equine influenza. Influenza vaccine should not be administered to foals less than 6 months of age due to strong and persistent maternal antibodies. Vaccinating too soon can lead to inadequate protection later in life.


    Which vaccines do my horses need?

    The American Association of Equine Practitioners (AAEP) and the American Veterinary Medical Association (AVMA) have recently come up with vaccination guidelines. The AVMA has categorized vaccines as core and risk-based. Core vaccines are those “that protect from disease that are endemic to a region, those with potential pubic health significance, required by law, virulent/highly infectious, and/or those posing risk of severe disease. Core vaccines have clearly demonstrated efficacy and safely and thus exhibit a high enough level of patient benefit and low enough level of risk to justify their use in the majority of patients.”

     Core equine vaccines include:

    •             Tetanus
    •             Eastern Equine Encephalitis
    •             Western Equine Encephalitis
    •             West Nile
    •             Rabies


    Every horse should be vaccinated for these diseases. Not long ago, there were sections of the country where there was no West Nile Virus. Unfortunately, that is no longer the case. Horse owners should also not become lackadaisical about a disease just because they haven’t heard of any cases in their area or they decide to save money by vaccinating for the disease “du jour” and not some of the basic ones. An example of this occurred in South Carolina when West Nile Virus first entered the state. Many owners chose to vaccinate for West Nile in place of Eastern Encephalitis. Unfortunately, South Carolina was about to experience a normal cyclical outbreak of Eastern Encephalitis that year. Hundreds, possibly thousands of horses died from encephalitis that year because they were not properly vaccinated.

     Risk-based vaccines include:

    •             Anthrax
    •             Botulism
    •             Rhinopneumonitis (equine herpes)
    •             Equine Viral Arteritis
    •             Equine Influenza
    •             Potomac Horse Fever
    •             Rotaviral Diarrhea
    •             Strangles
    •             Venezuelan Equine Encephalitis

    How do I decide which risk based vaccines to give?

    Horse owners should formulate a plan with their veterinarian as to which of the risk-based vaccines are appropriate for their horses.

    Registered 2011 Equestrian Collections; Author: Sallie S. Hyman, VMD, DACVIM, CVA

    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional. In particular, all horse owners should seek advice from a veterinarian for their horses medical needs.

  • Equine Leg Protection

    Equine Leg Protection

    The distal limb of the horse is a delicate structure comprised of not much more than bone, tendon/ligaments, and skin.  There is little natural protection for this area, unlike more proximal portions of the leg where thick muscles cover the area and protect the underlying structures from injury. 

    The main structures of the distal limb include: the extensor tendons on the front of the limb; the digital flexor tendons (superficial and deep) and suspensory ligament on the back of the leg; the cannon bone; the sesamoid bones; the heel bulbs; and the hoof.   All of these structures are vulnerable to injury if not adequately protected.

    How do horses injure their legs?

    Some horse are naturally more prone to injury of the lower limb than others due to their confirmation or way of moving.  They may "interfere" when they move, that is, one leg brushes the inside of the opposite limb when they travel.  This can happen in the front and hind limbs. Many owners will recognize this as small cuts, bumps, and abrasions on the inside of their horse's legs.  Some horses will "forge", that is, the hind limbs will reach far forward and catch the back of the front leg. This can result in pulled shoes or cuts to the heel bulbs or coronary band. 

    Of course, many of the activities we ask our horse to participate in, such as cross country jumping, racing, reining, and even shipping, put the lower limb at risk for injury. 

    What can we do to prevent injury?

    We can help to decrease injuries by using appropriate leg protection in the form of boots or bandages.

    Just what can or can't boots and bandages do?

    Boots and bandages can offer protection from penetrating wounds.  That is, wounds from hitting an obstacle, from an overreach of a leg, or from a fall.  Basically, they can help prevent the limb from being cut or scraped up.  Not all bandages offer the same level of protection from penetrating wounds, but most will help to decrease the severity.

    Boots and bandages cannot offer protection from concussive forces.  Concussive forces are the pounding the structures of the limb experience as a horse runs or jumps.  Boots and bandages cannot offer significant support to the limbs.  Even bandages with straps that wrap around or under the fetlock offer only minimal support to the limb.  Some owners believe that if they put the boot on as tightly as they can, then is will support the ligaments and tendons.  This is absolutely false and will likely result in pain, if not injury to the skin, tendons, and ligament of that leg.  

    What problems can boots or bandages cause?

    Boots and bandages can cause other problems if you are not careful.  Some boots will soak up water when they get wet.  This can double the weight of the boot.  Now imagine trying to navigate a cross country course with ankle weights on.  That is essentially what your horse is trying to do if he is wearing the wrong type of boot.  The  added weight can also change the flight of your horse's stride that can result in stress on joints and soft tissue structures. 

    Boots can also trap a lot of heat beneath them.  This heat can have serious detrimental effect on tissue, especially of the superficial digital flexor tendon.  A study out of Japan showed that exposing tendon cells to temperatures of 48° C (118.4° F) will result in the death of 80% of the cells.  Additional studies have shown that temperatures in the distal limb tissues will reach that high or higher.  If boots are added and prevent heat dissipation or increase the temperature, thermal damage to the flexor tendons can result.  The best way to prevent thermal injury is to remove the boots as soon as they are no longer needed ad to ice your horse's legs immediately.

    So how do I choose the correct boot?

    Fit, material, and function are the three most important elements to consider when choosing a boot or bandage.

    A boot must fit properly.  If it is too tight it will cause pain; if it is too loose it can slip and cause rubs or even trip your horse.  Boots that are molded must be especially well fit.  If not, they will cause more problems than they will prevent.  It may take several tries to find the style of boot that best fits your horse.  

    There are now a plethora of materials from which boots are made.  Leather boots have always been popular.  They must be properly cared for to prevent them from becoming too stiff to correctly fit your horse's legs.  Neoprene will conform to a horse's leg well, but they can produce and trap a lot of heat, and if dirt or sand gets under them they will cause rubs.  Plastic boots can have the same problems.  Polo bandages will offer some protection from cuts and abrasions, but not from significant impacts.  No material is perfect.  Chose the one that fits your horse's legs well, is easy for you to keep clean and maintain, and provides the level of protection you need  - i.e. just light protection from interfering vs protection from brush and solid fences out cross country.  

    Function is always part of the equation. Polo bandages work well on the polo field.  Open front leather boots are good for the show jumping ring.  Reining horses have their own boots for protecting fetlocks as they slide.  Find a boot or bandage that does what you need it to do.

    What about Bell Boots and Shipping Boots?

    Bell boots help to protect the coronary band, heel bulbs and hoof wall.  These boots are particularly helpful for horses that forge and tend to pull shoes or cut their heel bulbs.  Newer velcro styles have made getting bell boots on and off much easier.  However, the old fashioned "bell" style solid bell boot is still a great choice for horse that seem to the velcro undone no matter what.  

    Shipping Boots and bandages are used to protect your horse's legs from bumps cuts and scrapes while loading, shipping, and unloading.  They not give your horse's legs support.  Shipping boots should fit so that they don't flap and flop when your horse is walking to the trailer.  If they do, they are too big and will only cause problems.   If you use shipping bandages, they should be applied so that they cover the  heels bulbs.  If your horse does not like to be wrapped so low, you can use bell boots to protect his feet.  In that case, the bandages go from below the knee to just below the fetlock.

    If you keep in mind what protection boots and bandages can provide for your horse, and chose a proper fit and material for your purpose, you will be able to keep your horse a little safer when you embark on your next adventure.   

    Registered 2011 Equestrian Collections; Author:  Sallie S. Hyman,  VMD, DACVIM, CVA

    Registered 2011 Equestrian Collections; Author: Sallie S. Hyman, VMD, DACVIM, CVA

    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional. In particular, all horse owners should seek advice from a veterinarian for their horses medical needs.

  • Mini Horse Health

    Miniature Horse Health


    They’re little, they’re cute, but remember, they’re horses. They might fit into the back of the Suburban or even in the living room, but Miniature Horses need to be cared for like a horse. And now that we agree that these little guys are horses and even though Miniature Horses might seem just like their larger counterparts in, well, miniature, there are some differences. In addition to all of needs and medical issues that all horses face, Minis have a number of issues that are more common in that breed. Anyone thinking about getting a Mini should carefully read about their special needs and make sure that they are equipped to handle them.  


    There are several serious medical conditions that are common in Miniature Horses.



    Angular Limb Deformities—There are defined as a deviation from the normal axis of a limb as viewed from the front or behind. Minis are often born with severely crooked legs. This can cause trouble walking, abnormal hoof wear, and discomfort. Surgery can correct some of these deformities. 


    Upward Fixation of the Patella—In this condition, the patella of the stifle gets hung up on the medial (inside) trochlea of the femur and causes the stifle to become “locked” in extension. You might recognize this as a horse with a stiff, outstretched leg. Usually they can eventually “unlock” the patella by backing up. Upward fixation of the patellar can occur due to weakness in the muscles that support the patella, a too long medial patellar ligament, or straight hind limb conformation. In some extreme cases both hind limbs are affected and the Mini will stand parked out and unable to move forward. In such extreme cases, blistering of the medial patellar ligament, splitting of the medial patellar ligament, or even cutting that ligament may be necessary to correct the problem.


    Luxated Patella—Miniature Horses are prone to lateral luxation of the patella. This can result in a similar stance to a upward fixated patella or may result in-long term lameness. The patella luxates laterally (to the outside of the leg) due to congenital abnormalities of the stifle region including a shallower than normal femoral groove (where the patella slide) and a hypoplastic (smaller than normal) or deviated tibial crest. Surgery is necessary to reposition the tibial crest and to deepen the femoral groove.



    Malerupted teeth. Minis commonly do not lose their deciduous (baby) teeth. This makes eruption of the permanent teeth difficult and can result in overcrowding of the teeth. The deciduous teeth often need to be pulled.


    Overbite/Underbite. Deformities of the jaw are a common and serious problem. In brachygnathism, also referred to as an overshot mouth, or parrot mouth, the upper incisors hang over the lower incisors. In prognathism, also referred to as an undershot mouth, monkey mouth, or sow mouth, the lower incisors are in front of the upper incisors. Both conditions require frequent and proper dental care to keep the Mini’s bite correct. In severe cases, these conditions can prevent a Mini from prehending food.



    Sinusitis. The roots of the molars in the horse are located in the sinuses of the skull. When there is overcrowding of the teeth in the mouth, there is corresponding overcrowding of the tooth roots in the sinuses. This can prevent normal drainage of the sinuses and allow trapped bacteria to multiply and cause a sinus infection.



    Fecaliths. Fecaliths are firm rock-like impactions of manure due to poor mastication of food, poor quality feed that cannot be properly digested, or eating foreign materials such as baling twine, lead ropes, blankets, or tails. Fecaliths are commonly found in the small colon. Occasionally they can be encouraged to pass with fluids and mineral oil, but surgical removal is necessary in most cases.


    Enteroliths. Enteroliths are firm rock like masses that form from minerals in the diet that from around some nidus, such as a swallowed rock, nail, or other foreign material. Enteroliths can be found in almost any portion of the intestine, but tend to get stuck where the lumen size decreases. The same treatments as for fecaliths apply to enteroliths.


    Sand colic. Due to their greedy nature, Miniature Horses will scavenge every last piece of food off the ground. In the process, they will ingest a lot of sand if that is what is on the ground. If you keep you Mini in a geographic location where there is sand, test their manure frequently to see if they have accumulated sand and give them a sand preventative supplement, such as psyllium.


    Minis often do not exhibit the classic signs of colic. If your Mini goes off feed, lies down more than normal or is depressed, contact your veterinarian. Any Mini that is off feed for more than 24 hours is at risk for hyperlipidemia.



    Hyperlipidemia/Hepatic lipidosis. This is the most serious and most fatal disease of Miniature Horses. Pony breed, donkeys, and Minis are very susceptible to hyperlipidemia/hepatic lipidosis. These breeds store fat easily. If they go off feed for some reason or have stress place on them such as pregnancy, lactation, other diseases, their bodies will start to mobilize fat for energy. The liver processes the fat into energy. This is a very inefficient system and much of the fat ends up being deposited in the liver. This causes swelling of the liver and reduction in normal liver function. Eventually the liver will fail and death can result. Any Mini that is off feed for 24 hours is at risk for hyperlipidemia. Signs of hyperlipidemia/hepatic lipidosis include anorexia, fever, colic, diarrhea, jaundice, head pressing, circling, and death. Contact you veterinarian immediately if your Mini stops eating for more than 12 hours. The mortality rate runs between 60-100%, so swift intervention and treatment is necessary.


    Obesity. Miniature horses have evolved to be very efficient at utilizing minimal amounts of calories. It is imperative that you do not overfeed your Mini. Most do not require any grain. Hay should be available at a rate of 1.5-2% of body weight. Grazing should be minimized and taken into account when calculating the amount of hay given. Speak with your veterinarian to formulate a proper feeding program for your Mini.



    Abortions. Minis are prone to later term abortions (around 6 months). These are usually due to a malformed fetus.


    Dystocia. Due to the discrepancy between the maternal pelvic size and the fetal head size and limb deformities, dystocia (difficult birth) is common in the Miniature Horse. Once a mare’s water has broken, the foal should be delivered within 30 minutes. If the process takes any longer than that, veterinary assistance is vital and a caesarian section may be necessary.



    Dwarfism. Miniature Horses are meant to be small, but they are not dwarfs. Dwarfism is a genetic condition. Many forms of dwarfism exist. The two most commonly found types in Minis are achondroplasia (short limbs) and diastrophia (twisted limbs). Achondroplastic dwarfs can usually ambulate well and live fairly normal lives. Diastropic dwarfs have multiple limb deformities, domed heads, roached backs and generally need a great deal of support, including splints or surgery in order to ambulate properly.


    Anterior Segment Dysgenesis.  ASD is a condition of the eyes in which certain parts of the eye such as the cornea, iris, lens, ciliary body, and retina do not develop normally. One of the most common and apparent abnormalities is an enlargement of the cornea that gives the eyes a “bugged-out” look. Horses with ASD are at increased risk for vision loss. The condition was been associated with the gene for the “Silver-Dapple” color.


    Owning Miniature Horses can be a fun and enjoyable venture as long as you are armed with the information you need to be prepared for and to care for their special needs. 

  • Equine Dental Health

    Open Wide


    Dental care is critical for the health and wellbeing of your horse. Horses prehend and chew their food with their teeth, turning fibrous grasses into digestible calories and energy sources. When something goes wrong with your horse’s dentition, severe medical problems can arise.


    Horses are obligate herbivores. Their diet consists entirely of plant materials, in the form of grass, hay, or grains. Most of these feedstuffs require extensive mastication to release the digestible nutrients. The equine jaw and dentition are perfectly designed for this function. The front incisors are designed to cut the grasses and the premolars and molars form a flat grinding surface.   


    Dental Anatomy

    Horses have a total of 36-44 permanent adult teeth. There are 3 incisors (front teeth) on both the upper and lower jaws. The canines are next. There can be anywhere from 1-4 present. Stallions and geldings have well developed canines. These are the fighting teeth, used to settle territorial disputes and to protect their herd. Some mares also have small vestigial canines. Behind the canines is the interdental space. This area is also referred to as the bars of the mouth. There are no teeth in this area, just mucosa (gum) covered jawbone, and it is here, where the bit sits. Next come the wolf teeth if they are present. They are the first premolars. Sometimes the wolf teeth do not erupt, even though they are present. These are referred to as “blind” wolf teeth. Then the second, third, and fourth premolars. Finally come the first, second, and third molars. 


    Horses, like people, have 2 sets of teeth. The deciduous, or baby teeth, arrive fairly early. They start much like human teeth, with the first incisor coming through first. This happens at about 6 days of age. Then the second incisor at about 6 weeks of age, then finally the third incisor at 6 months of age. The second, third, and fourth premolars come in at about 2 weeks of age. The permanent of adult teeth begin to push through starting with the first incisor again at the age of 2.5 years. The permanent teeth then proceed as follows:    First incisor:                2.5 years

                            Second incisor:            3.5 years

                            Third incisor:               4.5 years


                            First premolar:             6 months-3years

                            Second premolar:        2-3 years

                            Third premolar:           2.5-3 years

                            Fourth premolar:         3-4 years


                            First molar:                  ~1 year

                            Second molar:             2 years

                            Third molar:                3-4 years

    As the permanent teeth are coming in, you may see some bumps on your horse’s lower jaw. This is just a result of the tooth roots pushing up through the jawbone and causing remodeling. Once these permanent teeth erupt, though, things are not over. The horse has what are called hypsodont teeth. These are tall teeth that continuously erupt throughout your horse’s life. The teeth erupt at the rate of about 1/8 inch per year.


    The upper arcade of teeth is slightly wider than the lower arcade. This helps to facilitate grinding as the horse chews in a circular motion. As your horse chews, the enamel surfaces grind across each other. Normally, there is slightly uneven (less) wear of the outside edge of upper arcade and the inside edge of the lower arcade. If there is uneven wear of the enamel elsewhere, sharp points and hooks can develop. Hooks normally occur on the upper second premolar and the last lower molar. All of these uneven edges can be sharp and cause trauma to the soft tissues of the gums, tongue, cheeks, and lips. Just imagine how painful a noseband can be is tightened over sharp edges that are sticking into your horse’s cheeks.  As these tall hooks develop, they also prevent the normal circular grinding motion of the jaws. You may notice your veterinarian sticking her hand in your horse’s mouth to feel for sharp edges and moving your horse’s lower jaw from side to side. This is to determine if there are any hooks or points that are inhibiting normal motion. 


    It is important to have your horse’s teeth examined by a veterinarian at least once a year. For young horses, this is necessary to make sure that the baby teeth have fallen out properly. Occasionally, a baby tooth won’t fall off and will be stuck on a permanent tooth. This “cap” will need to be removed in order for the permanent tooth to come in all the way. For older horses it is important that sharp points and hooks aren’t causing pain when chewing, limiting jaw motion, or causing problems with the bit. Other more severe problems can be found early and interventions can take place sooner rather than later. 


    Some of the most common dental problems are discussed below


    Wolf teeth. The first premolar is much smaller than the others and is not well rooted in the jaw. This can cause discomfort for a horse with a bit in his mouth. Wolf teeth are normally removed routinely for horses that will wear a bit to prevent any problems. As mentioned earlier, sometimes these wolf teeth do not erupt, but can be under the gums and cause problems. Your veterinarian can usually feel them under the gum and remove them. Sometimes a radiograph can help to locate them.


    Overbite and Underbite. An overbite, commonly called parrot mouth occurs when the upper jaw is longer than the lower jaw, placing the upper incisors in front of the lower ones.   In an underbite, commonly called monkey mouth or sow mouth, it is the lower jaw that is longer, placing the lower incisors in front of the upper ones. This limits your horse’s ability to prehend food and can cause imbalance in the mouth, especially preventing the molar arcades from contacting each other to grind effectively. Regular dental care can help to keep your horse’s bite as normal as possible. In some extreme cases, surgical correction has been attempted in young horses.


    Long canines. If the canine teeth grow to long, they can cut into the opposing soft tissue and cause pain. This is easily corrected by shortening the teeth.


    Step mouth. A step mouth occurs when one or two teeth grow especially long due to loss of the opposing tooth. With nothing to grind against, the tooth continues to grow longer than the rest. This will prevent normal chewing. Frequent dental attention to that tooth will keep it short and in line with the other teeth. Sometimes a very long tooth may require power tools or molar cutters to get it short.


    Wave mouth. A wave mouth occurs when the teeth have worn unevenly and have an undulating surface, looking much like waves when viewed from the side. This, too, will prevent normal chewing. The goal is to flatten the grinding surface so that normal mastication can take place.


    Other conditions that may occur include fractured teeth and tooth root abscesses. A thorough examination and radiographs can help to diagnose these problems and direct appropriate treatment.


    One condition that is not specifically tooth related, but is jaw related, is damage and fractures of the bars of the lower jaw. Some horses will incur damage to the bars of the mouth from the bit. Some horses can become painful on the bars from a particular bit. The gums and underlying bone can become inflamed and painful. Riding in a bitless bridle for a period of time until the area is no longer painful to palpation is the treatment. Fractures can also occur due to trauma and radiographs should be taken to investigate any pain or swelling in the area.


    Dental Care


    It is recommended that you have your horse’s teeth examined yearly by your veterinarian. Not every horse will need to be “floated”, that is have the sharp points and hooks filed down, every year, but it is important to check. Older horses and horses with known dental issues may require more frequent care. 


    Some signs that your horse may have dental issues include:


                Not eating

                Dropping food when eating

                Turning his head to chew

                Undigested food or long strands of hay in his manure

                Head shaking

                Resists bit, carries head to one side

                Grabs bit/chews bit    


                Bad breath/foul smell in mouth


    Have your veterinarian do a complete physical exam in addition to examining your horse’s teeth if any of these signs occur.


    By taking care of your horse’s teeth, you will end up with a horse that can maintain his weight, be free from dental pain, and be comfortable in his bridle. Don’t let cost make you put off dental care. It has been said that most horses will use their grain more efficiently when their teeth are well maintained, enough so that the reduction in feed costs more than pays for the annual dental exam. 


    Keep those teeth healthy and watch your horse smile! When he does, it will make you smile too.

  • Stable Vices

    Stable Behavior


    Inside or out? That is the million dollar question for many horse owners when it comes to choosing somewhere for their horse to live. We like to live in a nice house, so why shouldn’t our horses? Although most horses have learned to adapt to life in a stall, it is really not in their nature to live that way. The majority of horses will find the comforts of a stall pleasing and stress free, but for some, being confined can be the source of much stress and anxiety. Sometimes we have no choice when an injured horse requires stall rest or when adequate turn-out space is not available. By understanding equine behavior, we can help to reduce this stress and relieve some of the bad habits that can result from it.


    All horses, whether at pasture or in a stall will exhibit similar maintenance behaviors. There behaviors include eating, drinking, urinating, defecating, resting, and grooming.   A study presented by Dr. Sue McDonnell based on 24 hour surveillance video of mares in stalls showed the following behaviors and how much time was spent at each one:


    Behavior Norms for Mature Horse Mares in Box or Tie-Stalls Per 24-hour sample

    Major activity shifts

    30- 110 activity shifts; average of 20-60 min per activity

    Standing rest

    10-30 episodes; 5-120 min per episode; 8-12 hours total

    Recumbent rest

    0-6 episodes; 10-80 min per episode; 0-6 hours total


    10-30 episodes; 5-120 min per episode; 4-12 hours total

    Standing alert

    10-30 episodes; 5-30 min per episode; 2-6 hours total


    2-8 bouts; 10-60 sec per bout; 1-3 min total duration


    4-15 urinations


    4-15 defecations

    *hay fed 2-3 times daily or with hay available continuously


    Dr. McDonnell reports that these behaviors are also similar to what is observed in mares at pasture or even in wild horses. Geldings show similar patterns to the mares, with stallions and young horses showing slightly increased activity. Older horses show less activity, with more time spent at rest and eating


    A very interesting observation that Dr. McDonnell has made in her years of behavior research is that horses in a stall will walk as many steps and make as many movements per day as a horse out at pasture. This applies even to horses in tie stalls.


    Horses prefer to make all of these movements in the vicinity of other horses due to their social nature. They take cues form one other and develop social hierarchies. This applies even to stabled horses who may not share a paddock or a common stall wall. It seems as though horses just know who the boss is and they all respect that horse.


    So that is what normal behavior in a typical horse is. Abnormal behavior, or what we commonly refer to as “stable vices” is the subject of many studies concerning equine welfare. What we once thought of as “bad” behavior may have its origins in improper dietary management or in the lack of appropriate equine social interactions. Most stable vices fall into the category of stereotypies. Stereotypies are defined by behaviorists as behaviors that are “repetitive and invariant with no obvious goal or function and can be indicative of a situation in which the animal lacks a certain degree of control over its environment.” (Mason, 1991) (Winskill et al, 1995). Estimates put the number of affected horses at somewhere between 15-25% of the population. 


    The most common stereotypies relate to either locomotion or oral fixations. The locomotor stereotypies include weaving and stall walking. Weaving is a repetitive side-to-side motion of the head, neck, and front limbs. Rarely, the horse will weave with its hind end. Stall walking is the circling or pattern tracing constant walking around the stall. The oral fixations include cribbing and wind-sucking. Cribbing involves the horse biting onto an object such as a fence, door, or bucket before engulfing air and making an audible grunt. In wind-sucking, no object is grasped.


    These behaviors may be coping mechanisms used to decrease stress and not merely a means of getting attention or because a horse is bored. Several laboratories have shown that opiates are released during these behaviors and even when the stress is gone, many horses will seek the behavior for the reward of the opiate release. So why don’t all horses exhibit stereotypies when they are stressed. Just like in humans, different individuals have different means of coping. It has been found that there is likely a genetic component to the predisposition to developing a stereotypy, as the behaviors run in certain families of horses.


    There are many devices and techniques used to try to prevent these behaviors in order to prevent damage to the premises (fences, doors), to prevent horses from tiring or injuring themselves, and as many horseman think, from teaching other horses the behaviors. At least in the last case, teaching other horses these behaviors, research has shown that horses do not learn these behaviors from other horses. With the recent discovery that stereotypies are coping mechanisms for stressors in a horse’s life, it is now questioned as to how humane it is to try to stop the behavior without first identifying and removing the stressors. 


    So what can you do to reduce the stress and help to decrease stereotypies in your horse?


    If you horse is a cribber or wind-sucker, look to change your horse’s diet. Recent research has found that cribbing may help to increase alkaline salivation thereby decreasing the acidity in the stomach. By decreasing the concentrate in your horse’s diet, feeding more hay, and administering an antacid, you may decrease of eliminate the cribbing/wind-sucking behavior. 


    Stall weaving seems to result from the lack of social interaction with other horses. Research has found that placing a 3 ft x 3 ft safety mirror on the wall in a horse’s stall will dramatically reduce (as much as 97%) the amount of weaving that a horse does. The mirror provides a “friend” to your horse and calms his stress. The mirror also helped to decrease stall walking.


    If you horse has to spend time in a stall, you can make some management changes to help reduce his stress, make his “in” time more enjoyable, and help to decrease the chance that he will develop any bad habits. 


              1. Give you horse a buddy. See if you can keep another horse in an adjacent stall to keep your horse company. If you cannot, consider getting a stall  mirror. Make sure it is a safely mirror. Many equine stall mirrors are now       available commercially.

              2. Reduce the concentrate in your horses diet and increase the amount of      hay he gets. Consider treating with an antacid as weill.

              3. Give you horse some means of entertainment, such as jolly balls, hanging toys, and hanging salt licks.

              4. Allow you horse as much turnout with other horses around as possible (if  medically permissible). Your horse doesn’t need to be in the same paddock        as the other horses, just in adjacent ones if you are worried about injuries.


    We are learning so much about equine behaviors every day. What used to label a horse as a “bad egg” has been shown to be a way to deal with stress. As we deal with these welfare issues and try to decrease the amount of stress our horses face, we will be able to decrease what we find to be undesirable behaviors.

  • The Prepurchase Examination

    The Prepurchase Examination


    You’ve spent weeks, months, sometimes even years looking through the “for sale” ads trying to find the perfect horse just for you. He’s beautiful, rides like a dream, everything you wanted and more. Finally, your search has ended. But don’t put him on your trailer just yet. You should never purchase a horse without first doing a prepurchase examination. 


    A prepurchase examination is just what it sounds like. A veterinarian examines the horse your are interested in before you make the actual purchase to make sure that the horse is healthy and sound at the time of purchase. Skipping the prepurchase examination because the horse is free, inexpensive, or owned by someone you know “so I know he’s doing his job”, is a surefire way to end up with expensive veterinary bills and an unusable horse in the future.


    If you are one of the lucky few, the horse of your dreams will be sound and have no problems. Many buyers, and more often, the sellers, fear the prepurchase examination because they feel it is a witch hunt to find something wrong with the horse. That is not true. The purpose of the examination is to find out what issues a horse has and if they will interfere with the horse doing his intended job and if the buyer is in a position to manage those issues. Very few horses, especially those that are competing frequently, are completely sound and many horses need veterinary interventions to keep them sound. That is not something that should automatically be a deal breaker. Again, the prepurchase examination will let you as the buyer know if you are comfortable dealing with whatever issues the horse has. The prepurchase examination cannot tell you if a horse will become lame in the future. It is merely a snapshot in time, on that day, letting you know if he will be suitable for your purposes. Some information your veterinarian gathers may hint at future problems, but, especially in the case of a completely sound horse on the day of purchase, future problems cannot be predicted. 


    Prepurchase examinations come in all shapes and sizes. A basic prepurchase examination may include just a thorough physical examination and checking the heart, lungs, eye, and gastrointestinal system. More comprehensive examinations include a detailed examination of every body system, a moving examination with flexions to check for soundness, a neurological examination, radiographs, ultrasounds, and nuclear scintigraphy.. 


    The Exam


    Every examination should start with the seller filling out a form detailing the horse’s past medical history, including any lamenesses, illnesses, medications he is currently on, as well as any maintenance treatments, such as joint injections or shock wave treatments that he received and when he last received them. 


    The most basic examination should consist of listening to the heart/lungs/gastrointestinal system, taking the horse’s temperature, examining his skin/coat, and palpating his legs for any abnormalities.


    A true prepurchase examination will consist of a thorough physical examination and a moving examination with limb flexions to check for lameness. During the physical examination the following systems should be checked:

                1. Skin/hair coat/lymph nodes—also check for any scars from prior surgery

                2. Cardiovascular system—should be checked prior to and after exercise

                3. Respiratory system—should be checked prior to and after exercise.

                4. Gastrointestinal system

                5. Eyes—should be examined with an ophthalmoscope

                6. Teeth, oral cavity—will help to age horse as well

                7. Temperature

                8. Urogential system—especially if animal will/may be used for breeding

                9. Nervous system—complete neurological examination

              10. Musculoskeletal system—hoof test all four feet and observe shape and quality                 of hoof. Note if barefoot or shod and type of shoe. Palpate limbs for splints,                           pain, tendon/ligament abnormalities. Palpate back for soreness. Flex neck and                     back. Watch horse walk and trot in a straight line and in a circle in both                              directions on a firm surface. Repeat on a soft surface if possible. Do flexion                      exams of front and hind limbs to check for lameness that might be exacerbated                 by stressing the joint. In some cases in may be helpful for your veterinarian to                        see the horse being ridden as well.


    Radiographs of the major joints of the limbs are usually performed to check for any abnormalities. The areas most frequently radiographed include: The front feet, all 4 fetlocks, the hocks, the stifles, the carpi, the neck and the back. Radiographs can tell you if arthritis, degenerative joint disease, OCD lesions, or mineralization in soft tissues is present. 


    After the examination is complete, additional diagnostics may be performed to further evaluate the horse. These include upper airway endoscopy, ultrasound of any areas of concern in soft tissue structures, diagnostic nerve blocks to isolate the area of lameness if present, and nuclear scintigraphy.


    How much or how little you choose to do will depend on several factors, however, no horse should be purchased without your veterinarian seeing it for at least the most basic of examinations. Ideally, every horse would have a full exam and full set of radiographs.


    These factors include:            


    1. The age of the horse. Weanlings and yearlings can usually be purchased with just a basic examination. Ocular problems, such as cataracts or retinal abnormalities, heart murmurs or dysrhythmias, umbilical hernias, and angular limb deformities can be picked up on a basic examination. Two-Five year olds should have a complete examination with a full set of radiographs to look for OCD lesions. Horses older than 5 should have a complete examination and full set of radiographs. You may choose to focus radiographs just on any areas of concern if your budget is limited. Aged horses should have a complete physical examination to make sure they are physically safe for any activity, especially if they are going to be used as beginner horses for children.


    2. Yours or resale. Is this going to be a resale horse or one for your own use. A resale prospect should have a complete examination and radiographs to make sure that you are not surprised by anything when a potential buyer does their prepurchase exam. A horse for your personal use will ideally have a full exam and radiographs, but if your budget is limited, you may pick and choose some of the diagnostics.


    3. Use of horse. A horse that is going to be used as a leadline pony will not need as extensive an examination as a horse that is going to be used as a grand prix show jumper. All horses should have a good physical examination. A horse that is currently in full work and competing and is expected to continue to compete should get a full exam and radiographs. This also applies to a horse doing a lower level than what will eventually be expected of him. 


    The prepurchase examination is a way to know what the health status is of the horse you are buying. It is not a pass/fail venture. It is a roadmap to know where your horse stands from a health and lameness perspective and what you will need to know and do to keep him going for your purposes. The prepurchase examination is a worthwhile investment when choosing your new horse and should be calculated into your budget. Even a free horse is worth getting an examination done on. Those few hundred dollars you spend now may help to save you thousands of dollars and lost riding time in the future. Knowledge is power, and by knowing what you are buying, you will be able to enjoy your new horse with few surprises. 


    Congratulations on your new horse. Now you can worry about other things, like what color blanket to get him!

  • Foaling

    Equine Foaling 101 or “Happy Mother’s Day”


    You paid your stud fee, ensured that your mare is pregnant, gave her the best medical care and nutrition during her pregnancy and patiently waited almost a year. Now the time has come for her to foal. What should you know and do to make sure that all of her (and your) hard work results in a healthy and safely delivered foal?


    There are many foaling alarms and monitoring systems, in addition to old-fashioned checking on the mare, to know when your mare is about to deliver. It is best to get the mare acclimated to lights on in the foaling stall and whatever else you plan to have on when the time arrives so that you don’t startle her. A mare can stop stage one labor if she feels threatened. Have a clean, large foaling area prepared. The mare should be acclimated to the stall as well. Signs of impending parturition include development of the udder (can occur as early as 2 weeks prior to foaling), waxing of the teats (usually within 36 hours of foaling), relaxation of the ligaments around the tail head, and lengthening of the vulva. 


    In preparation for foaling, be sure to have a few items on hand. A tail wrap or clean roll gauze should be used to wrap your mare’s tail and a bucket of warm water and roll cotton to clean the vulva.   Have lots of clean towels to help dry the foal if necessary. And have your veterinarian’s phone number nearby, just in case there are any concerns.


    Mares have a gestational length of 335-342 days. Some go a little earlier, some go a little longer. Previous gestational length is a strong indicator of future pregnancy length. So if your mare foaled at 335 days last year, she will likely deliver at 335 days this year. Any foal delivered at 320 days or earlier is considered premature and should receive immediate veterinary care. 


    In order to fully understand the foaling process, it is important to understand the anatomy of the equine placenta. The placenta consists of three layers. There is the amniotic layer that surrounds the foal. The other two layers are attached and called the chorioallantois. The chorionic surface attaches to the uterus via microvilli that give it a red velvety appearance. There are no villi at the cervical star, the area where the chorioallantois apposes the cervix. The allantois has a whitish/blue shiny appearance. When the foal breaks through the placenta, usually at the cervical star, and the normal birthing process continues, the placenta will become everted as it is pulled behind the foal by the umbilical cord. 


    Parturition (foaling) is divided into three stages. Stage I usually lasts 1 to 4 hours. During this stage the uterus begins contracting and the foal is positioned for delivery. The mare may act restless, pace the stall, get up and down frequently, urinate frequently, and sweat. Stage I ends when the chroioallantois ruptures, i.e. water breaks. Some mares don’t show outward signs and Stage I is only recognized when the chorioallantois ruptures. If the mare will tolerate it, now is the time to prepare the her by foaling. Wrap her tail and wash her perineum and udder. 


    Stage II is the actual delivery of the foal. It is a very swift and explosive stage and should last no more than 30 minutes. The mare will experience strong contractions and the amnion will rupture at this point. The foal should begin to be delivered head and front feet first. It is best to let the mare manage this stage on her own as long as there are no complications. Occasionally it is necessary to gently assist the delivery by pulling the foal in a downward direction when the mare is pushing. If stage two lasts more than 30 minutes, or you recognize that the foal is not positioned correctly, it is time to get your veterinarian out. Another sign that requires immediate veterinary attention is a “red bag” delivery.   If instead of seeing the water filled amniotic sac or the foal’s nose or feet, you see the red velvety allantois, the placenta has separated from the uterus and the blood supply (i.e. oxygen supply to the foal) is compromised. Call your veterinarian to come out immediately and advice on what to do until she arrives. You may be instructed to rupture the membranes and assist the delivery. In most cases, however, all will go well and the foal will be delivered without incidence. Once the foal is out, resist the temptation to jump right in. This may startle the mare and cause her to jump up and rupture the umbilical cord prematurely. The foal receives several liters of blood through the umbilical cord right after birth. Stage II ends when the umbilical cord ruptures. Once the foal is up, dip the umbilical cord with 7% iodine. Repeat several times over the next few days to help to prevent umbilical cord infections.


    Stage III if the final stage of parturition. During Stage III the placenta is delivered. This usually occurs within 4 hours of the foal’s delivery. The mare may begin to cramp and appear to go into labor again. Do not attempt to pull the placenta out. It can tear and leave pieces within the uterus. This can lead to life-threatening uterine infections and laminitis. If the placenta has not passed after 4 hours, call your veterinarian. She will provide treatments such as oxytocin to stimulate uterine contractions, flush the uterus with saline, and administer antibiotics and anti-inflammatories to combat infection and toxemia. 


    Let your mare bond with her foal before you jump in to start handling it. She will clean it and lick it dry and encourage it to stand and nurse. If it is extremely cold when the foal is born, it is all right to help dry it off more quickly to help keep it warm. Most foals stand and nurse within an hour of birth. Call your veterinarian if the foal does not stand or attempt to stand within an hour, doesn’t latch on and nurse, has any limb deformities (contracted tendons, lax tendons), you see milk come out its nostrils, or starts out strong but then fades and won’t get up after a few hours. 


    Watching you mare foal can be an exciting and wonderful experience. Knowing what to expect will help you recognize when something is not going right and assistance is needed and also allow you to relax and enjoy the foaling process.


  • Foals: What to Watch For

    Foals: What to Watch For--The first few hours, the first few days


     The spring season brings with it the long awaited arrival of foals. Once your mare and foal have bonded it is time to do a thorough examination of the foal to make sure that everything is within normal limits.


    The initial exam should consist of a TPR (temperature, pulse rate, respiratory rate). Newborn foals, those less than one week of age, have different “normals” than adults. Normal temperature in a newborn foal is 99.5-102, higher than an adult horse. Normal heartrate (HR) for a foal is greater than 60 beats per minute (bpm) and can range from 80-100 bpm during the first day. Normal respiration rate (RR) is 30 breaths per minute, with the range from 20-40 breaths per minute. The heart and lungs should be ausculted for any abnormal sounds such as murmurs, irregular rhythms, or crackles and wheezes. Gastrointestinal sounds can be ausculted with a stethoscope as well.

     Rib Fractures

    The rib cage of newborn foals should be carefully palpated to feel for any rib fractures that may have occurred during parturition. Fractured ribs are painful can cause serious damage is a sharp broken end lacerates the artery that runs along the rib, or in some cases, can puncture the lungs or heart. Any concern or question about possible rib fractures should be brought to your veterinarian’s attention. Radiographs or ultrasound may be needed to confirm the fractures. Some can be managed conservatively, while others may require surgery to stabilize them.


    The foal’s abdomen should be palpated for the presence of any body wall hernias. These can occur in the umbilical, inguinal, scrotal regions. A hernia is a protrusion of tissues or organs through an abnormal opening. In foals umbilical hernias are most common. The area surrounding the umbilicus is one of the last areas of the body wall to close during development. Incomplete closure of the body wall results in a defect that can be palpated as a hole in the muscular body wall. Normal foals will have a very small hole (smaller than the tip of a finger) at the umbilicus that will gradually shrink and disappear as the umbilicus dries up and falls off. Umbilical hernias usually appear as a soft sack on the underside of the belly and can vary in size from just a few centimeters to very large (up to 12 cm). Umbilical hernias should be non-painful and the contents should be easily reduced back into the abdomen. For smaller defects, reducing the contents into the abdomen several times a day may allow for them to close. Larger defects will require surgical correction.

    Failure of Passive Transfer

    Foals should be up and nursing within 1-3 hours of birth. It is very important for foals to ingest this first milk, known as colostrum, as soon as possible, and definitely within 24 hours of birth. Colostrum is very important because it is rich in antibodies, protein and calories. The mare transfers her antibodies to the foal primarily through the colostrum. These antibodies protect the foal against environmental diseases. These antibody proteins are also called immunoglobulins or "IgG". They are very large in size. The foal's small intestine will only absorb these large proteins during the first 12-24 hours after birth. After 24 hours, the only way a foal can absorb more immunoglobulins is by a plasma (intravenous) transfusion. It is recommended that a veterinarian check the foal's IgG levels within the first 12-16 hours after birth. A normal IgG level is greater than 800 mg/dL. A level of 400-800 md/dL indicates partial failure of passive transfer. A level of less than 400 mg/dL is considered complete failure of passive transfer. Without these antibodies, your foal is susceptible to disease. If the foal's IgG <400 mg/dl, the foal has a 25% chance that it will contract a disease if exposed. If the foal's IgG< 200 mg/dl, the foal has a 75% chance it will contract an environmental disease if exposed. Your veterinarian can pull blood from your foal and do a stall side test to measure the IgG level and determine a course of action. If you get a low reading before the foal is 24 hours old you can supplement with oral colostrum. If it is past 24 hours, them IV plasma is needed. Most foals tolerate plasma transfusions well and it can be done on the farm.


    Once a foal is up and nursing, it should start passing its first feces (meconium) within a few hours. The foal will pass multiple small piles of meconium. All of the meconium should be passed within 24 hours. The meconium is dark brown, firm fecal balls. If the foal is straining a lot, you can give a Fleet enema to help the foal pass the meconium. After all of the meconium has passed, the foal will start to defecate thick, pasty, orange colored  milk feces. This is a good sign indicating that milk has made its way through the entire digestive tract. Not nursing, straining, rolling up on their backs, and teeth grinding are all signs of colic in foals.

     Lax and Contracted Tendons

    Newborn foals often are born with lax tendons that make it look like they are walking on the backs of their fetlocks. Confining the foal to a stall for a day or two usually will resolve the problem. Wraps are not indicated, as they may weaken the muscle/tendons more, but you can put a light “band-aid” of vetrap on the limbs if they are getting rubbed.

    The opposite condition, called contracted tendons in foals, is more serious. These foals appear very upright. The fetlocks or pasterns may even buckle forward. This condition can be painful, as the foals try to stretch the overly tight tendons. This may prevent them from standing and nursing. Mild cases can benefit from physical therapy (stretching exercises and controlled exercise. More severe cases can be treated with IV oxyteteracycline that helps to bind calcium and causes muscle relaxation (and by extension, tendon relaxation). Therapy is usually repeated for up to 3 days. Bandages can be helpful in these cases.

     Ruptured Bladder

    Occasionally during delivery, a foal’s bladder can be ruptured. This happens most commonly in colts (90%). Signs of the rupture usually become apparent within 1-7 days after birth. The foal’s abdomen may become enlarged from the urine leaking into it, the foal will become depressed, may show signs of colic, and might dribble urine. Electrolyte abnormalities will begin to occur as the urine accumulates in the abdomen (uroperitoneum). Contact your veterinarian if your foal is straining to urinate, doesn’t pass a good stream of urine, or has an enlarging abdomen or is becoming depressed.

    Neonatal Isoerythrolysis (NIE)

    NIE is an immune mediated hemolytic condition inherited from the stallion. The mare produces antibodies against the foal's red blood cells which have a marker on them inherited from the stallion. The antibodies produced by the mare are concentrated in the colostrum. The foal is normal at birth. But after ingesting the antibodies in the colostrum, these antibodies attach and destroy the foal’s red blood cells. The foal typically shows signs of weakness, jaundice (yellow coloration of the gums, white of the eyes, vaginal mucosal) and anemia within 12-24 hours.. Prevention is key. If the mare has a history of NIE foals, the mare can be tested 2-3 weeks prior to the foaling date. The mare is crossmatched with the stallion (stallion red cells and mare serum), during this time when exposure to the foal's erythrocytes is likely to occur (thus boosting the antibody titer, if there is an incompatibility). If there is any question of NIE, the foaling should be attended. The newborn foal should be muzzled the first 24 hours and fed an alternate source of colostrum. The mare's milk should be stripped (milked) out the first day. This condition is rarely seen in maiden mares, and is more commonly seen in foals when the mare is bred back to the same stallion carrier. Treatment includes a whole blood transfusion if it is diagnosed early enough. Severely affected foals may required hospitalization with oxygen therapy.


    Septicemia, an infection in the blood stream, is a serious and life threatening condition of foals. Infection can enter the blood stream through many routes, including via the placenta (in utero), umbilicus, gastrointestinal tract, and lungs. Foals may be sick at birth or appear normal at birth and quickly deteriorate in condition. Signs of septicemia include fever or hypothermia (foals often get colder, not hotter, when they are sick). Other signs include loss of suckle reflex (you can often recognize this by observing a full bag on the mare or the mare may be squirting milk), lethargy, depression, or recumbency. Septicemia is diagnosed based on complete cell count (very high or very low white cell count), high fibrinogen, and a blood culture. Antibiotic therapy is crucial and should be based on culture when possible, but broad-spectrum therapy should be instituted while waiting for the culture. Septic foals may require supportive therapy such as plasma transfusions, oxygen, oral or IV nutrition, and anti-inflammatories.

     Dummy Foals

    Neonatal maladjustment syndrome, hypoxic-ischemic encephalopathy, dummy foals. There are many names to describe what results from lack of oxygen during parturition due to placental separation, dystocia or septicemia. Several other syndromes due to lack of growth in utero or dysmaturity can also present with similar signs. These foals can show signs of seizures, irritability, spastic movements, inability to suckle, wandering, or barking (abnormal vacalizations). This is a very serious condition and requires intensive and often prolonged treatment. Many of these foals will go on to lead normal lives if their cases are not complicated by sepsis or other infections.

     This is by no means a comprehensive list of everything that can wrong with foals, but it does give a good overview of what to be on the lookout for when your bundle of joy hits the ground. Knowing what is normal, and abnormal will help you keep you foal healthy from the start.

    Registered 2014 Equestrian Collections; Author:  Sallie S. Hyman,  VMD, DACVIM, CVA  

    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional.  In particular, all horse owners should seek advice  and treatment from a licensed veterinarian for their horses' medical care.  

  • Pain Management

    Pain Management in Horses

    Every horse owner is familiar with pain. Horses colic, get a scratch on their cornea, or go lame. We know something is wrong because they act painful. But what exactly is pain? 

    The International Association for the Study of Pain (IASP) defines pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.” The IASP adds, “The inability to communicate verbally does not negate the possibility that an individual is experiencing pain and is in need of appropriate pain-relieving treatment.” Pain involves the sensory reception of a noxious stimulus that evokes a response, usually a withdrawal from the noxious stimulus. This is a protective mechanism that helps to keep us and animals from becoming injured by whatever noxious stimulus we just experienced. There is an emotional component to pain as well. We learn that a certain stimulus will cause pain and therefore we avoid it in the future. Our bodies are rich with pain receptors, called nociceptors. These are unmyelinated nerve endings that are present in vast numbers in the skin, joint capsules, muscles, and internal organs, basically anywhere pain can be felt. The main body of these cells is located within the spinal cord. The nociceptors are stimulated and release neurotransmitters that send signals through the spinal cord, up to the brain, are processed, then the evasive action is transmitted back down the spinal cord and is initiated. There are several types of nocioceptors. Mechanosensitive nocicpetors respond to pressure. Thermorecptvie nocioceptors respond to temperature. Polymodal nocicpetors respond to pressure, temperature, and chemicals released by injured cells. Inflammation causes many of these chemical messengers that cause pain to be released. This is how pain and inflammation are related. Adaptive pain is helpful pain. It produces responses and behaviors that avoid the painful stimulus and promote healing and recovery. If adaptive pain is not appropriately managed, physical changes occur in the central nervous system (spinal cord and brain), leading to maladaptive pain. Maladaptive pain is unhelpful pain that is out of proportion to the actual tissue damage and persists long after the injured tissues have healed. Maladaptive pain is very difficult to control. The changes to the central nervous system make the nervous system more sensitive to stimuli, even in the face of treatment and healing. The longer pain goes unmanaged, the more likely it is to undergo the change from adaptive to maladaptive pain and the harder it is to manage. This is true for both acute and chronic pain. With this basic understanding of the neurophysiology of pain, it is clear why some cases of what should be easily controlled pain are more difficult to manage than expected.


    Treating pain can take many forms. Traditionally medications are used. Other methods to treat pain include rest, hydrotherapy, electrostim therapy, acupuncture, extracorporeal shock wave therapy, laser therapy, and ultrasound therapy. This article will focus on medications.


    There are many different pain medications available today. The common pain medications we use in our equine patients belong to the classes of steroidal, non-steroidal, and opiate pain relievers. They come in many different forms such as intravenous and intra-articular preparations, oral medications, and topical ones as well. Each medication has a specific function and appropriate use of it will ensure that you are safely and effectively treating your horse.


    Steroidal anti-inflammatories


    Inflammation produces a host of mediators that can cause direct stimulation of pain receptors or cause tissue damage that in turn stimulates pain recpetors. The pathway of inflammation is mediated by arachidonic acid that is further broken down into two inflammatory mediators. The first is prostaglandin that is produced from arachaionic acid by cyclooxygenase. The second is leukotrienes that are produced from arachidonic acid by 5-lipoxygenase. Steroids prevent the production of arachidonic acid and therefore prevent further inflammation by preventing the production of prostaglandins and leukotrienes. This blocks the entire cascade, also preventing the production of good prostaglandins that protect the lining of the stomach. Steroids do not directly act on pain receptors. They stop the production of chemicals that stimulate those receptors. Steroids are most commonly used to treat inflammation of joints and are injected into the affected joint to minimize unwanted side effects when given systemically. Topical steroids are used to decrease inflammation and pain in certain ocular conditions. It is imperative that you do not treat a corneal ulcer with steroids. Use steroids in the eye only under the advice from a veterinarian. Common steroids used for pain management include methylprednisolone, triamcinolone, and prednisolone. Steroids should be used only when recommended by your veterinarian. 


    Non-steroidal anti-inflammatories


    Horse owners are usually most familiar with this class of drugs. It includes phenlybutazone, flunixin meglumine (Banamine), ketoprofen (Ketofen), firocoxib (Equioxx), aspirin, and meclofenamic acid (Arquel).   The NSAIDs block the cyclooxygenase enzyme, interrupting formation of thromboxane, prostacyclin and the prostaglandins from arachidonic acid. Recent research has also shown that some of the NSAIDs act on pain receptors in the central nervous system and block pain in the same way as drugs like morphine. There are two types of cyclooxygenase (COX) enzymes, COX-1 and COX-2. The products of the action of COX-2 on arachidonic acid are the bad prostaglandins that result in inflammation. The products from the action of COX-1 are actually protective against inflammation and maintain the health of the gastrointestinal tract, the renal tract, and proper platelet function, among other functions. Blocking the products from the action of COX-1 is detrimental to your horse’s health. Older NSAIDS are non-specific cyclooxygenase inhibitors. Phenylbutazone, flunixin meglumine, aspirin, ketofen, and meclofenamic acid are all non-specific COX inhibitors. Side effects from these medications include gastrointestinal ulceration and renal disease (from decreased blood flow), impaired platelet function tract, and diarrhea and protein loss from mucosal damage to the gastrointestinal tract. Firocoxib is a newer NSAID that is a COX-2 inhibitor. This helps to minimize the side effects seen with the older NSAIDS. Many horses are on long term NSAIDS for chronic pain and minimizing side effects if desirable. Phenylbutazone, flunixin meglumine, aspirin, and firocoxib are available in both injectable and oral forms. Ketoprofen is injectable only. Meclofenamic acid is an oral products. One NSAID is available as an ointment. Surpass, diclofenac sodium, is available in a preparation that allows it to be applied to the skin and is absorbed locally where the inflammation is. There is minimal to no systemic absorption of the drug and there for no adverse side effects. 



    The nervous system contains receptors that respond to opiates. Stimulation of these receptors causes euphoria, sedation, pain relief, hallucinations, and in humans, addiction. There are three types of opiate receptors, “mu”, “kappa”, and “sigma”. Opiates work in several ways to produce their effects. Receptors can be stimulated (agonized) or blocked (antagonized). Some opiates will only stimulate receptors and are called “pure agonists”. Others can block some receptors and stimulate others. These are called “mixed agonist/antagonists”. The most commonly used opiate pain medication in horses is butorphanol. It is mixed agonist/antagonist. Fentanyl is another opiate used in veterinary medicine. It is available in adhesive patches that slowly release the medication over an extended period of time. Unfortunately, fentanyl patches are not effective in the horse. Opiates are controlled substances and should be administered by a veterinarian only. 


    Alpha-2 agonists

    Xylazine and detomidine are alpha-2 agonist sedatives that also have analgesic properties. Analgesia is produced by binding to receptors in the spinal cord, thus inhibiting the release of neurotransmitters. These sedatives are useful for producing sedation and mild analgesia when your horse undergoes minor procedures that may cause mild discomfort such as teeth floating and suturing small lacerations, but are not suitable for long term pain management.


    Many horses suffer from acute or chronic pain that requires careful treatment. The goal is to alleviate the pain as quickly as possible with the least amount of side effects. For horses with chronic pain, it is often necessary to try different medications to see which one is most effective for that particular horse. Many horses with chronic pain are still able to perform, but need to be medicated. Make sure that you check with your veterinarian to make sure that you are not violating any association rules when you mediate a performance horse that is competing. There are mandatory withdrawal times for certain medications and a new rule that restricts treatment to just one NSAID at a time. These rules are in place for the welfare of your horse. 


    Pain can be, well, a pain. Veterinary medicine has made tremendous strides in helping to reduce and control pain in our equine patients. Careful, judicious use of the correct medications at the correct time can greatly improve your horse’s comfort whether he is recovering from an injury or surgery, keeping comfortable in retirement, or easing the aches and pains of competition.

  • Draft Horses


    Diseases of the Draft Horse


    Draft Horses are the gentle giants of the equine world. These massive horses were originally bred for pulling.  They have short backs and well-muscled hindquarters that make them ideally suited for pulling heavy loads. Their placid and willing temperaments make them easy to work with. They were an integral part of early farming and industrial life, as well as instrumental during times of war. They continue to be an important part of farming life today, as well as enjoyed for their skill in carriage driving and in sport such as pulling competition.


    There are many breeds of draft horse, but all share common characteristics of strength and calm temperament. The most common draft breeds recognized today include: Shires, Belgians, Clydesdales, Percherons, Friesians, Brabants, American Cream Draft, Fjords, Spotted Drafts, Haflingers, Gypsy Vanners, and the Suffolk Punch. Many of these breeds stand 16-19 hands tall and can weigh up to 2200 lbs.


    Draft horses have their share of medical problems, some of which are quite specific to the draft horse or certain breeds of drafts.


    Probably the most widely known condition that affects Draft breeds is Equine Polysaccharide Storage Myopathy (EPSM). In EPSM there is a build up of glycogen and abnormal polysaccharide in the skeletal muscles. Affected horses are not able to properly metabolize starches and sugars due to an abnormality of glycogen synthesis regulation that results in deposition and storage of unmetabolized carbohydrate in the muscles.   The muscles are not able to use these abnormal polysaccharides for energy and suffer an energy deficit. Muscle fiber necrosis ensues as well as catabolism of muscle and a decrease in muscle fiber size. EPSM is believed to be an autosomal recessive trait. Mares appear to be affected more than geldings. The symptoms of EPSM include muscle weakness, especially following exercise, muscle wasting, muscle fasciculations, exercise intolerance, reluctance to exercise, intense sweating with exercise, and recumbency. Signs are often recognized in young horses when they begin training, but signs can develop at any age. Some horses show symptoms every time they are exercise, while others will have only a few episodes per year. Diagnosis is made based on blood work (increased muscle enzymes CK and AST), muscle biopsy, and now genetic testing using hair is available. There is no cure for EPSM, but many horses can be managed through dietary modification. The goal is to significantly reduce sugar and carbohydrate from the diet and replace them with fat. 20-25% of daily calories are supplied via fat. Grass hay should be fed. To see a complete EPSM diet, please see Dr. Beth Valentine’s recommendations at Exercise is also very important for these horses. They should have consistent daily exercise for best results. Rest is contraindicated for these horses unless they have had a severe bout of muscle weakness or muscle damage.


    Azoturia/Tying Up/Rhabdomyolysis/Monday Morning Disease

    Azoturia is the release of muscle breakdown products into the urine as a result of muscle damage. In draft horses, it is thought to be related to underlying EPSM. Muscle damage occurs with exercise and results in muscle pain, cramping, recumbency, and discolored urine. The symptoms are usually less severe than with EPSM and muscle enzyme (CK and AST) levels are increased less than with EPSM. Any draft horse that has an episode of azoturia should be tested for EPSM. Treatment consists of changing the diet to that recommended for EPSM and keeping your horse in consistent work.



    Shivers is a neuromuscular disease that affects the hind limbs of horses. It is most common in draft breeds. One or both hind limbs and the tail are affected. The symptoms include trembling of the hind when flexed, trembling of the tail when raised, difficulty backing up with the limb occasionally getting “stuck” in midair and trembling until it is gradually lowered, muscle atrophy, and difficulty picking up the hind feet to clean the hooves or to be shod. Most owners recognize that there is a problem with their horse when they try to work with the hind feet. Too often, horses are thought to be misbehaving when they will not easily pick up their hind feet. Punishing horses for this will only exacerbate the problem. Symptoms can worsen then the horse is excited or stressed. Patience is needed to work with these horses. In some cases, the disease progresses to the point that the hind feet can no longer be trimmed or shod. The cause of Shivers is still unknown. Although some horses suffer from both EPSM and Shivers, there is no definitive connection between the two diseases.


    Chronic Progressive Lymphedema

    Chronic Progressive Lymphedema (CPL) is a progressive swelling, hyperkeratosis, and fibrosis of the lower limbs. It is related to the syndrome in humans that causes elephantitis. Shires, Clydesdales and Belgians are affected. This disease has also recently been found in a small number of Gypsy Vanners. There are ongoing studies to determine what, if any, genetic components are involved in the development of the disease. Currently researchers are investigating the genes that control elastin and vascular endothelial growth factor (VEGF). It is also thought that there is a hereditary component to the disease, so it is important not to breed affected animals The disease can start at a very early age and, as the name implies, progresses throughout the life of the horse. It is usually first noticed as a mild case of pastern dermatitis (“scratches”) that does not respond to traditional therapy. When closely examined, thickened skin, often with thick skin folds and crusting lesions are present. It is imperative to clip away the heavy feathers on the horse’s lower leg to be able to adequately examine the limb, as well as to eventually treat the area. The thick feathers are suspected to play a role in the development of the disease. Over time, the lymphatic drainage system in the skin becomes inflamed and fibrosed and no longer functions properly. This, in turn, leads to lymphedema, fibrosis, decreased perfusion, a compromised immune system, and secondary skin infections. The lower limbs become grossly enlarged with thickened skin folds and nodules that affect mobility. The average age of the severely affected horse is 15 years. This makes screening for breeding purposes difficult. Severe infections can develop with non-healing oozing wounds. Many horses eventually have to be euthanized due to the severity of the disease. There is no cure for CPL. Symptomatic therapy includes clipping the feathers, keeping the limbs clean and dry, treating any mild symptoms aggressively, controlling infections and using compression bandages. Compression bandages have been shown to be of some benefit for some horses. These bandages must be applied correctly in order to be effective and not to injure the horse. Please have your veterinarian show you how to correctly place them.


    Junctional Epidermal Bullosa

    Junctinal Epidermal Bullosa is a hereditary disease of Belgian Draft horses. This protein is necessary for the adhesion of the skin layers. Lack of this protein causes the skin to be very fragile and to rub off and blister at pressure points. In addition, there is formation of ulcers in the mouth and on the tongue, and sloughing of the hooves. Affected foals die within a few weeks of birth. Euthanasia if recommended as soon as a diagnosis is made due to the painful nature of this condition. There is a genetic test now to determine if a horse is a carrier of the mutated gene. The gene is a recessive trait, so it takes one copy from the dam and one from the sire to produce an affected foal. Known carriers should not be used as breeding animals.


    Ocular Squamous Cell Carcinoma

    Draft breeds are more susceptible to squamous cell carcinoma tumors of the eyelids and eye than other breeds.


    Belgian Cataracts

    Belgian Draft horses have a high incidence of cataracts.


    Nutritional Needs

    It is a common misconception that draft breeds need more grain due to their large size. The truth is that draft breeds have lower energy requirements than lighter breeds of horses, and therefore, require less grain on a per pound of body weight basis. Many owners feed based on the amount listed on the feedbag and are grossly overfeeding their horses. This can result in obesity and even laminitis. Less is often more for these horses. Since these horses are getting fed less than what the manufacturers recommend based on body weight, they are sometimes not getting the full amount of nutrients that they need. For horses on EPSM diets or for very easy keepers who do not get much or any grain, a good vitamin/mineral supplement and possibly a protein supplement is necessary. Ask you veterinarian what is needed for you horse to make sure that all of his nutritional needs are being met.


    Draft horses are some of the most gentle, willing, and wonderful horses out there. It is important to know what medical concerns are specific to these breeds in order to care for them properly and to enjoy what they are willing to do for us.

  • Hay Basics

    Hay Basics


    Horses are herbivores, designed from their teeth to their digestive tract to eat plants. Equine teeth are flat and broad and form a crushing surface to grind plant material. About 65% of digestive capacity takes place in the horse’s cecum and large colon, the lower gut of the horse. Beneficial bacterial populations that help to break down fibrous material colonize these portions of the gut. Horses need to consume a minimum of 1% of their body weight in long stem forage per day in order to maintain proper gut function. When horses do not receive enough forage of the correct size, problems with digestibility and nutrient absorption can occur. Horses in light to moderate work need a total of 2-2.5% of their body weight in total feed per day. Ideally, most of that is fed in the form of hay. Recent studies have shown that horses fed high grain, low forage diets colic more frequently, develop gastric ulcers and exhibit behavioral problems such as cribbing. Eliminating the grain and increasing the hay in these horses alleviated behavioral problems in many of these horses. Forage is best consumed as pasture, but when that is not possible due to lack of acreage or seasonal conditions, then good quality hay should be fed. 

    There are many types of hay that can be safely fed to horses. Geographic conditions usually dictate what types of hay are grown in an area. Some common types of hay include: timothy, alfalfa, orchard grass, coastal bermudagrass, pangola, brome, clover, and fescue. No matter what type of hay you feed, it is important to get good quality, clean hay. Clean hay means no dust or mold. Hay contains upwards of 19mg/m3 ( milligrams of respirable irritants per cubic meter of air). It takes just 0.43mg/m3 for disease to start. Adding dust and mold to hay can cause significant permanent lung damage such as heaves in horses that are continuously fed bad hay. 

    There are many factors that go into determining the quality of hay. Most horse owners are looking for a green, clean and fresh smelling bale that appears free of weeds, pests (such as blister beetles), and foreign objects. These are all good characteristics to look for, but knowing the hay maturity at harvest has the greatest impact on quality. Hay should be harvested during the vegetative stage or just thereafter. Plants in the vegetative stage do not have visible seedheads (grasses) or flowers (legumes). Plants at this stage have higher protein concentrations. As plants mature, they lose protein and the non-digestible carbohydrate lignin content increases. Lignin decreases the overall digestibility of the hay. Immature hay has a higher neutral detergent fiber content (a measure of cell wall content). A higher NDF makes a hay more readily consumed.

    Hay should be analyzed to properly determine its quality. It is important to get a representative sample to be analyzed. Core samples 3/8 inches in diameter and 12-18 inches long should be taken from several (10-20) bales of hay, mixed together, and then a pooled sample if sent in for analysis. There are several methods to accomplish this. Chemical analysis is the most complete method. It can determine the protein, structural and non-structural carbohydrate content, as well as, the trace mineral and vitamin content. The downside to chemical analysis it that it is expensive and has a slow turnaround time. Near Infrared Reflectance Spectroscpy (NIRS) can determine the protein and carbohydrate content, but cannot give the trace mineral content. It is, however, a less expensive and faster way to analyze hay if only a crude analysis is necessary. Contact your local agricultural extension office for exact instructions for submission in your area. The analysis report will include data such as crude protein, calcium, phosphorus, phosphate, acid detergent fiber (lignin and cellulose content), neutral detergent fiber, relative feeding value (how readily the hay will be consumed), and dry matter. Your local extension officer should be able to help you understand your report and offer suggestions for supplementation.

    Horse owners are always concerned that they are feeding their horse the right kind of hay. While horses can thrive on just about any type of good quality hay, there are certain types of hay that are more appropriate for different types of horses. Different hays have different nutritional values and different horses have different nutritional requirements. The magic is to match up the two correctly. Horses with lower energy requirements such as healthy retired horses or horses in light work can do very well with late maturity hays. This type of hay has a lower nutritional content and more can be fed without causing the horse to gain weight. Broodmares, weanlings, and horses in heavy work will do better eating early maturity alfalfa and grass hay. Horses with gastric ulcers can benefit from alfalfa in their diet due to the high calcium content that acts as an antacid. The debate continues on whether alfalfa hay is good or bad for horses with laminits. Keeping the non-structural carbohydrate content low is probably the most important aspect of feeding the laminitc horse. Not all horses can be maintained on a hay only diet and will require some supplementation with grain. All horses should have access to salt and mineral blocks. 

    Problems with hay

    Feeding hay is very safe and the preferred diet for almost all hoses. There are a few problems that can arise and are discussed below.

    Blister beetles

    Blister beetles are members of the genus Epicautus. The beetle if found in the semi-arid regions of the Western United States. They produce cantharidin, which is toxic to people and animals. The adults feed on alfalfa and are often caught up in the hay during the baling process. Dead beetles are just as toxic as living ones. Cantharidin causes irritation of the urinary tract, gastrointestinal tract, and occasionally if fatal. Signs of blister beetle poisoning include blisters in the mouth and on the tongue, diarrhea, bloody diarrhea, blood in the urine, difficulty with urination, and colic. If your horse exhibits any of these signs after eating alfalfa hay, call your veterinarian immediately and save any uneaten hay for inspection.

    Fescue Hay

    Tall fescue hay is often infected by an endophyte fungus called Acremonium coenophialum. Broodmares consuming endophyte-infected tall fescue during late gestation may experience prolonged gestation (as long as 13 to 14 months), dystocia or foaling difficulty, thickened placenta ("red bag" foal) or agalactia (a decrease or absence of milk production), and reduced breeding efficiency following parturition. Foals may be born weak or dead. Endophyte-infected tall fescue apparently causes few adverse effects in non-pregnant horses. It is recommended that pregnant mares be removed from endophyte infected fescue pastures 60-90 days before their foaling date.

    Coastal Bermudagrass

    Coastal bermudagrass is a very fine, soft hay that does not require a lot of chewing on the part of the horse in order to swallow. As a result, long strands of hay are swallowed and can mesh together into a ball that can become lodged in the part of the small intestine (the ilieum) that enters into the cecum. These “hay balls” will cause an impaction that blocks the small intestine. Horses will develop pain and exhibit signs of colic. This should be treated as an emergency and your veterinarian should examine and treat your horse. Some cases can be managed medically with analgesics and fluid therapy, but many require surgery to remove the impaction.

    Clover slobbers

    Clover (red, white, and alsike) and occasionally alfalfa, can become infected with the fungus Rhizoctonia leguminicola . This fungus produces the mycotoxin slaframine or slobber factor. Horses who ingest infected clover will have hypersalivation. Although the hypersalivation is harmless to your horse, it can be extremely profuse and annoying to deal with. The toxin persists in hay, although its activity decreases after about 10 months of storage. No treatment in necessary. Remove the feed source of the clover and your horse will stop drooling.

     Moldy sweet clover

    Moldy sweet clover hay can contain high levels of dicoumerol, an anticoagulant, produced by the action of molds on coumerol, a natural component of sweet clover. Dicoumerol ties up Vitamin K and causes the blood not to clot. The toxin is stable in hay for up to 4 years. Animals show signs associated with hemorrhage, such as reluctance to move due to blood in joints, anemia, increased heart rate, and death. Mildly affected animals often respond to treatment with vitamin K and blood transfusions. Veterinary care is critical.


     Sudangrass/sorghum hybrids (Johnson grass) produce prussic acid only when on pasture. Prussic acid is related to cyanide and inhibits oxygen utilization in the body. Animals will exhibit signs of labored breathing, staggering, collapse and death. Death is usually sudden and can occur in as little as 20 minutes after consumption. Mildly affected animals can be treated with sodium nitrate to bind and inactivate the cyanide. Horses will preferentially avoid Johnson grass in a field as long as other forage is available. The toxin declines greatly in hay during the cutting and curing stage and is seldom a problem in well cured hay.



    Many types of hay are sprayed with preservatives in order to aid in curing and storage. The most common preservative is proprionic aced. Proprionic acid has been found to be safe when fed to horses. One study did find when given a choice, horses preferred preservative free hay compared to preserved hay, but would consume all of the preserved hay if it was the only choice.


    Hay should make up the bulk of your horse’s diet and that requires a lot of hay. Many horse owners wonder how much hay they should plan to buy. A rough estimate for a horse with no access to pasture is 600-700 lbs /month/horse. This amount is adjusted up or down based on the size of your horse (mini vs.draft) and the amount of pasture available. Hay will store well and retain its nutritional value for up to 2 years if kept in a clean, dry area. So if you find good, clean, nutritionally sound hay, feel free to stock up. It will keep and it will keep your horse well fed and healthy.

    Registered 2012 Equestrian Collections; Author: Sallie S. Hyman, VMD, DACVIM, CVA

    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional. In particular, all horse owners should seek advice and treatment from a licensed veterinarian for their horses' medical care.

  • Barn Safety

    Safety In and Around the Barn

     Winter is upon us and both people and horses are spending more time in the barn.  Now is the perfect time to do a barn safety check to make sure that you and your horses will be safe and stay healthy indoors.

     Keeping Safe

    Barn safety boils down to a lot of common sense and good planning.  First and foremost, keep a first aid kit around, for both people and horses.

    Tools and Clutter

    It is critical to keep aisles and doorways unobstructed.  This means making sure that things get put away where they belong.  Horses will, if given a chance, injure themselves on just about anything left in their way.  Wheel barrows, pitchforks, brooms, etc. should be put away where a person or horse cannot become entangled in or injured by them. Having all items put away and out of the aisles will keep exists open in case of an emergency. 


     Speaking of keeping items out of the way, make sure that all chemicals, bleach, lime, drain cleaners, etc. are out of the reach of children and animals. Both are curious and could end up with a mouth or eyeful of something that is harmful. Keep the poison control phone numbers handy in case of accidental ingestion.  Human poison control is 1-800-222-1222.  Animal poison control is 1-888-426-4435.  It is run by the National Animal Poison Control Center at the University of Illinois.  A fee is charged for information by the animal poison control center.  Keep other emergency numbers handy as well, such as Fire, Police, Ambulance, Veterinarians, and horse owners. 

    Electrical Hazards and Light Fixtures

     We usually think of “spring cleaning” as the time to knock down all of the cobwebs, but it is just as important to do so in the winter.  Cobwebs can be a fire hazard and collect dust that is unhealthy.  Dust and cobwebs over lights and electrical outlets is definitely a hazard.  Use a vacuum to suck the dirt and cobwebs out of outlets.  Do not use a leaf blower.  That will only blow the dust further into the receptacle.  Any receptacle that is near water should have a ground fault interrupter (GFI).  This will prevent you from getting shocked.  Check to make sure that light fixtures are securely attached.  Overhead lights should be hung high enough so that a horse cannot hit them, even if rearing.  If this is not possible, then all light bulbs should be covered with metal safety cages to prevent them from breaking if hit.  Check all areas of the barn for any nails that may have come loose that could cause a cut eyelid or nostril. 

    Fire Safety

     Fire safety is of extreme importance.  And wintertime is the most important time to think about it.  Horses spend more time in their stalls.  Most barns stock up on hay and bedding for the winter and store it in the barn. Horse barns are not regulated the same way as many other livestock facilities, and certainly not like residential homes in terms of fire safety design or prevention.  Think about what a barn consists of.  It is usually constructed of wood, stalls are bedded with straw or wood shavings, and the loft or some other area is filled with hay and bedding materials.  This makes for an extremely combustible mix.  It takes only 2-3 minutes for straw in a stall to ignite and burn a 10x10 foot area, burning at temperatures of 300 degrees.  Thermal injury to a horse will occur when they are within 6 feet of that fire in their stall.  In order to get your horse out unharmed, he must be evacuated within 30 seconds of the fire starting.  That is not a lot of time, so prevention is the best defense. 

    There are ways, however, to help keep your barn fire safe.  Have a fire evacuation plan.  Keep fire extinguishers at all exits, in the tack room, and anywhere else you want one.  Have smoke detectors in the barn that are kept clear of dust and cobwebs, that have working batteries in them, and are checked at least twice yearly to see that they are in working order.  If at all possible, store hay and bedding in a separate building.  For many people, this is not possible.  In that case, make sure that your hay is dry and cured before you store it in the barn.  Drying hay produces a lot of heat and actually combust and start a fire.  There are temperature probes you can get to check the temperature of the hay to make sure it is not dangerous.  Stack the hay properly to ensure good air flow to help heat dissipate and to prevent mold. 


     As a veterinarian, the most important concern for me when horses spend time in their stalls is proper ventilation.  Many horse owners anthropomorphize and believe that their horses want a nice warm, cozy barn, in the winter, just like we want.  Horses are designed to withstand the cold and keeping the barn locked up tightly is actually detrimental to their health. (Clipped horses will need blankets.) Ideally, a barn should be only 5-10 degrees warmer than the outside temperature in the winter.

  • Calming Supplements

    Calming Supplements ... Do They Work and Are They Safe?

    Any horse owner with a young or nervous horse has thought that there has to be some way to help their horse deal with stress.  There are a plethora of products available that aim to do just that.   A number of vitamins, minerals and herbs are used to help horses relax and focus in hopes of allowing them to perform better. 

    Do Calming Supplements Work?

    There is little research in the equine world to prove or disprove the effects of calming supplements. A few controlled studies regarding L-tryptophan show no calming effect on horses.  Despite the lack of evidence form controlled studies, calming supplements are very popular and many horse trainers and owners report anecdotally that they have seen improvements in their horse's behavior and performance when using them.

    Are Calming Supplements legal?

    Calming supplements should be used during training only.  It is against the spirit of fair competition and the mission of the governing bodies of equine sports to use these supplements during competition.  Valerian and its metabolites are prohibited during competition.  Magnesium sulphate injections are prohibited as well.  FEI and USEF are constantly reviewing herbal and other substances and developing testing techniques to identify those that they feel should be banned.  All horse owners should make sure they are aware of all ingredients in any supplement they use and check with the governing body of their discipline if they have any questions about the legality of any ingredient.  

    Here is a summary of the most commonly used substances in calming supplements.  Be sure to follow the dosing recommendations carefully.  More is not better!  In some cases liver damage, neurological abnormalities, or hemolysis can occur with use and/or misuse.

    L-trytophan is an essential amino acid (it must be supplied in the diet).  It is converted to serotonin, a neurotransmitter that helps to control mood by calming anxiety, relieving depression, and aiding sleep.  Most horse owners know about tryptophan due to its reputation  for being the culprit for sleepiness after eating turkey at Thanksgiving.  In reality, turkey has the same amount of tryptophan as other types of poultry.  Low doses have been shown to actually cause excitement in horses and extremely high oral does can product hemolysis (breakdown of red blood cells) due to conversion of tryptophan to indole (a hemolytic metabolite) in the digestive tract.

    Valerian (valeriana officinalis) is a tall perennial hearb with white to pinkish purple flowers.  The root is used medicinally.  The name valerian comes from the Latin work vlare that means "well being."  Over 150 phytochemicals have been isolated from valerian root.  The ones that shown to have shown to have sedative effects on the central nervous system include:  valerenic acids, valepotriates, GABA, tyrosine, arginine, and glutamine.  The effects of valerian root in humans are somewhat dose dependent with lower does relieving anxiety and nervousness, and higher doses aiding sleep. 

    Magnesium is a mineral that is essential for healthy function of almost all body systems.  In the body it is found as an ion within the cells.  Along with calcium, Magnesium helps to control muscle activity and nerve conduction. Calcium stimulates activity, whereas,  magnesium decreases or suppresses activity.  Magnesium has been found to decrease nerve exitation, decrease adrenaline secretion, decrease cortisol release, and to decrease muscle contraction by binding to intracellular ATP and breaking the actin-myosin bounds that cause muscles to contract.  In very high doses magnesium acts as a laxative and can cause muscle weakness.

    B vitamins are essential for converting food to fuel.  They also help to stabilize lactate levels that can cause anxiety.  Likely B vitamins largest impact on calming is due to its use a co-factor in the production of serotonin and norepinephrine.

    Kava Kava (piper methysticum) is a tall shrub with large heart shaped leaves and roots that look like bundles of woody, hairy branches.  The roots are ground up and used medicinally.  The teas has long been a traditional ceremonial drink in the Pacific Islands.  Kava kava contains kavlactones, specifically kavapyrones that reduce convulsions, promote sleep, and cause muscle relaxation.  The tea produces relaxation and a feeling of well being.  There have been cases of liver damage reported in humans.

    Inositol is a carbohydrate (previously thought to be B-vitamin) that functions a signaling molecule.  It can modulate serotonin activity, thus producing a calming effect.

    Red Raspberry Leaf (Rubus idaeus) is a source of magnesium and B vitamins.  Studies both in vitro and in vivo show that use of the leaves  either as a tea or an extract relaxes uterine muscles.  The active compounds have not been definitely identified.

    Chamomile (matricaria chamomilla) is an herb with a small white daisy like flower with a yellow center that is a member of the aster family (which also includes ragweed).  The flower contains volatile oils that contina the active ingredients bisabolol, apigenin, iluteolin, and matricin.  Bisabolol has antispasmodic and anti-inflammatory properties.  The constituents responsible for the sedative properties of chamomile have not been identified.  The sedation is only mild.

    Black Cohosh (actaea ra cemosa and cimicifuga racemosa) is a member of the buttercup family, a perennial plan that is native to North America.  The roots are used medicinally.  One active chemical is a saponin called 26-deoxyactein, but its mode of action is not known.  Black Cohosh is most often used for female reproductive issues.  A recently identified compound called fuinolic acid has some estrogenic activity.  There have been a few isolated cases of liver failure in humans taking Black Cohosh.

    Passion Fruit (passiflora incarnate) is a perennial creeping vine native to the Southern U.S. and South America.  The whole of the above ground parts of the plant are dried and used to make tea.  The plant contains alkaloids, glyosides, and flavanoids that in combination product the plants sedative effect.  The plant also contain naturally occurring serotonin and maltol, which has sedative effects. 

    Ginger (zingiber officinalis) is a herbaceous, perennial plant native to South Eastern Asia that is grown there, as well as extensively in Jamaica.  The rhizome is used medicinally.  Ginger contains oleoresins that are rich in gingerols.  These compounds have a variety of sedative effects.

    Calming Supplements are a training aid that can help your horse get through sticky period, but they are no something to be depended upon.

  • Cold Weather Riding

    Baby It's Cold Outside!

    Winter is upon us and most of us still want to ride. For those of us not lucky enough to be able to spend the cold season in warmer parts of the country, here is some information on effects that cold weather riding has on your horse, and how to keep him healthy and safe despite the cold temperatures.

    What temperature is really considered cold?

    Cold is relative to where you live. Riders in Florida may shiver at 50°F, whereas riders in Minnesota might not think twice about tacking when the thermometer reads 0°. Meteorologically speaking, cold weather is generally defined as an air temperature of 40°F or below. Wind, snow, ice or rain will increase the effect of the cold.

    What does exercising in cold weather do?

    Exercising in cold weather affects your horse's body in many ways. Bodily systems react in different ways. Most research on exercising in cold weather has been done on human subjects, but there has been studies on the effects of cold air on equine pulmonary function. Horses are actually used as an animal model for pulmonary research in humans, since the equine pulmonary function is similar to humans. A series of experiments were performed at Oklahoma State University investigating the deleterious effects of strenuous cold weather exercise on airway function in horses. These studies were designed to mimic the conditions that cold weather human athletes, such as skiers, experience. Many skiers develop cold induced asthma, often called skier's asthma. This occurs due to acute airway obstruction when cold air gets down into the lungs and damages tissues.

    Inspired air is conditioned (warmed and humidified) by the upper airways to prevent cooling and desiccation of the lung parenchyma. Although this process is usually successful, under severe conditions such as strenuous exercise in frigid environments unconditioned (cold and dry) air penetrates into the peripheral airways.

    In the OSU equine study, horses were exercised on a treadmill while breathing in chilled (4°C) air. After exercising, a bronchoalveolar lavage was performed to test for inflammation, cytokines (chemicals that can damage the lungs) and chemicals that can suppress the immune function in the lungs and lead to infection. Horses that exercise in cold weather experienced peripheral airway mucosal injury due to the penetration of unconditioned air. Furthermore, these results suggest that airway cooling and desiccation may be a factor in airway inflammation commonly found in equine athletes. Results of this study support the hypothesis that exercising while breathing cold dry air alters the airway cytokine profile. The study did not find an increase in inflammatory cells, but as the cellular response takes longer to occur, this study many not have been long enough for it to occur. These results support the contention that exercise while breathing cold air can actually contribute to the development of asthma. The data further raises the possibility of local suppression of cell mediated immunity thought the increased expression of interleukin-10.

    What does all this mean for the typical owner and rider?

    Basically, the take-away message from these studies are that horses' lungs can be damaged when strenuously exercised in cold temperatures. If the temperatures get really cold, keep the exercise light to prevent pulmonary problems, especially if your horse has heaves.

    Does cold only affect the lungs?

    Cardiovascular: The cardiovascular system (heart and blood vessels) react to cold by increasing the blood pressure and heart rate. It also reduces the amount of blood that flows closest to the skin in order to preserve core body temperature. The reduces blood flow to the skin can lead to frostbite. Th is lack of blood leads to the eventual freezing and death of skin tissue in the affected areas. Again, it is probably wise to reduce the intensity of your ride so that your horse's heart does not have to work so hard.

    Musculature and Joints: Muscles take longer to warm up in the cold weather and arthritic joints may ache and need more time to loosen up. If you are riding, even if you are riding less than you do in the warmer months, don't stop any joint supplements that normally help your horse. He will need them just as much, if not more, in the cold weather. You can also consider a quarter sheet to cover your horse's hind quarters. This will help to keep some heat in, without being restrictive, especially if your horse is body clipped. This brings up the question of whether or not to clip. If your horse gets sweaty when ridden, it is probably a good idea to so some sort of body clip, to help him cool out quicker. A sweaty horse will get very cold in cold weather if not properly cooled out dried off. There are many different types of clips so choose one that is right for your horse and your situation.

    Energy and Calories: Exercising in cold weather uses more energy than in warmer weather. Glycogen stores (glucose stored in the liver) is used up five times faster in cold weather. Once this is used up, the body start to convert fat for energy, which is less efficient. Make sure that any horses that will be working hard in cold weather are receiving an adequate number of calories.

    Hydration: Water consumption should be carefully monitored in the equine athlete who is working in cold weather. Dehydration occurs in cold weather just as much as it does in warm weather. Flavored electrolytes in feed or water may entice your horse to drink more If your horse is dehydrated, he will have reduced blood volume. that in turn, will make it harder for his already hard working heart to try to work harder to pump less blood. Make sure that your horse has plenty of fresh, liquid water around. A full frozen water trough does no good! Some horse prefer water warmed, so consider using trough and bucket warmers.

    Feet: Take care when there is ice and snow on the ground. Slippery conditions can lead to a whole host of musculoskeletal problems. If your horse is shod, consider snow pads to keep snow and ice from balling up on the bottom of his feet. Always pick out any snow or ice to help prevent slipping. Borium on the shoes can add traction, as can caulks if needed.

    Strenuous exercise in cold weather can be difficult on your horse. Common sense and information about how cold weather affects him will empower you to be able to create a cold weather exercise plan that will keep your horse fit, keep him happy and safe, and keep you in the saddle all winter long.

    Registered 2012 Equestrian Collections; Author: Sallie S. Hyman, VMD, DACVIM, CVA

    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional.  In particular, all horse owners should seek advice  and treatment from a licensed veterinarian for their horses' medical care.  

  • Equine Hoof Abscesses

    Ouch!  My Foot Hurts ...!

    During your routine morning check on your horse, you find him three legged lame.  You can't see anything wrong with him, other than that one foot is warmer than the others and he really doesn't want to put any weight on it.  Don't panic! Do, however, call your veterinarian immediately and arrange for an evaluation.   In most cases, your horse probably has a hoof abscess.  

    The weather on the East Coast this winter has been warmer and wetter than normal, leading to muddy, wet pastures.  These conditions have resulted in an increased number of hoof abscesses.  Just what is a hoof abscess and how can you help to prevent them, and treat them so your horse will sound and ready to go as quickly as possible?

    First, let's examine the structure of the hoof.

    The external hoof consists of the coronary band, the periople, the hoof wall, the white line, the sole, and the frog.

    • The coronary band (sometimes called the coronet) is a tough vascular structure that is considered the upper most portion of the hoof.  It sits between the skin and the hard hoof wall.  It helps to dissipate the concussion on the soft tissue structures within the hoof wall during each stride.  It also products the tubules of the outer hoof wall.
    • The periople is a protective layer that covers newly formed hoof wall just below the coronary band.  This structure often has a whitish appearance when wet.  The hoof wall consists of an inner and outer layer.  The inner hoof wall layer is usually white in color and is easily identified in a freshly trimmed hoof.  This layer is more pliable and has a higher moisture content than the outer layer.
    • The outer hoof wall is usually pigmented.  It provides protection to the structures beneath it and regulates the moisture content of the hoof.   The outer wall is designed to store and release energy during the phases of the stride to help propel the horse.
    • The white line actually appears more yellow than white and is where the sole and hoof wall join.
    • The sole is the bottom of the foot.  The frog is a thick, rubbery, triangular structure on the solar surface of the foot.  It is designed to absorb shock, provide traction, and assists circulation in the digital cushion of the foot.   

    The most important internal structures of the hoof are the coriums and the digital cushion. 

    • The coriums produce the elements of the hoof capsule.  For example, the solar corium produces the sole, the frog corium produces the frog, the coronary corium produces the hoof wall, etc.  These structures are very vascular and sensitive to any condition that can compromise their blood supply.
    • The digital cushion sits between the coffin bone and the frog.  it is a spongy structure that acts as a shock absorber though a complex transfer of blood through venous plexi.

    So what is a hoof abscess?

    An abscess is a localized accumulation of pus and debris located within the layers of the hoof capsule, most commonly subsolar or submural.  Abscesses usually occur one of three ways: a penetrating wound to the hoof; bacterial migration through cracks, nail holes, or a damaged white line; or by damage to the coriums due to decreased blood flow.

    Migration of bacteria is the most common cause of abscesses.  The white line gets damaged by moisture, dirt, or other debris and makes a tract for bacteria to get into the hoof capsule.  The soft tissues become inflamed, white blood cells migrate to the area, and the bacteria fight back at the white blood cells by releasing enzymes that cause tissue liquefaction.  This liquefaction leads to the grey/black "pus" that often explodes out of an abscess.  The inflamed area becomes walled off and becomes an abscess.

    The inflammation and encapsulated area puts pressure on surrounding tissues causing the pain associated with abscesses.  This area of pus will try to find the easiest place to drain.  Sometimes it can find a way out through the bottom of the sole, but often times, it will find an easier way through the soft tissues of the coronary band.  This is often referred to as a "gravel" when an abscess breaks out at the coronary band.

    How do I know my horse has an abscess?

    Most hoof abscesses present as acute lameness.  One day your horse is perfectly sound; the next he is three legged. Some abscesses will start out as a more subtle lameness and progress, but most are seemingly overnight.

    The signs, aside from the lameness, include heat in the foot and an increased digital pulse.  You can feel for this pulse by palpating the artery that runs on the inside and outside of the fetlock.  Normally a faint pulse can be felt. With an abscess, the intensity of the pulse increases greatly.

    Testing the hoof with hoof testers is the next step.  Most abscesses will be localized to a very specific area, although occasionally, a large subsolar abscess will cover the entire sole.  Radiographs are not normally taken, but your vet may take one to rule out a fractured coffin bone.  Swelling in the pastern and fetlock area may occur in abscesses that migrate toward the coronet.

    How do I treat an abscess?

    Treatment consists of providing a means of drainage for the abscess.  Your farrier or veterinarian can use a hoof knife to try to establish drainage of the white line where your horse was sensitive to hoof testers.  It is not recommended to dig a hole in the main portion of the sole.  This rarely provide relief, makes a defect in the sole that prove slow or difficult to hear and can open up an area of bacteria to invade and cause a bone infection on the coffin bone.

    If the abscess has started to  migrate dorsally to the coronet, a veterinary podiatrist (a vet who specializes in feet) or a farrier working with a vet can establish drainage through the dorsal hoof wall.  A very small hole is created in the hoof wall to relive the pressure and allow drainage.  It is thought that making the hole in the hoof wall is more humane than the pain that your experiences waiting for the abscess to make its way up to the coronary band.  The defect that results in the coronary band from the rupture of  an abscess can also affect the quality of the hoof permanently. 

    To encourage drainage of an abscess, horse owners can soak the affected foot in warm water with Epson salt, and wrap the foot with a drawing solve such as ichthamol, or animalintex.  Mild discomfort may not require anti-inflammatory medications such as Equioxx, but severe cases should receive some medication for pain relief.  Antibiotics are usually not necessary unless a secondary cellulitis develops or there is a penetrating wound.

  • Bute and Banamine

    More is Not Always Better - Bute and Banamine®

    Non steroidal anti-inflammatory (NSAIDS) medications are useful for treating many maladies in the horse, and are a staple in many first aid kits.  Phenylbutazone (Bute), flunixin meglumin (Banamine®), ketoprofen (Ketofen®), and firocoxib (Equiqioxx®) are the most commonly used NSAIDS.  Many horses with acute or chronic lameness receive some type of NSAID alone or in combination, often for extended periods of time.

    How do NSAIDs work and what are the risks?

    We are now aware of the many deleterious side effects of NSAIDS in the horse.  The nonspecific COX inhibitors such as phenylbutazone, ketoprofen, and flunixin meglumine can cause gastrointestinal ulceration and renal dysfunction.  These NSAIDS work by blocking prostaglandin production throughout the body.  Blockage of prostaglandins results in decreased inflammation and pain, which is the desired effect.  Unfortunately, blocking prostagladin pathways also results in decreased blood flow to some parts of the body, including the lining of the gastrointestinal tract and the kidneys.  This result in damage to the tissues and can lead to GI ulcers and decreased kidney function or failure.  The COX-2 inhibitor firocoxib is designed to lessen the potential effects on the GI tract and kidneys, but it is also not without some potential side effects.  

    How are dosages determined?

    The pharmaceutical companies have spent many years and many millions of dollars to develop these drugs and to determine the correct dosages and dosing schedule for them.  These dosages are formulated to maximize the positive effects, i.e. pain management for NSAIDs, and to minimize the negative side effects. 

    When it comes to NSAIDs, more is not better.  Altering the dosage, the dosing schedule, or combining two NSAIDs can prove to be harmful.  A recent study performed by Dr. Jonathan Forememan and Dr. Rebecca Ruemmler at the University of Illinois set out to determine the efficacy of phenylbutazone, flunixin meglumine, and a combination of  the two on experimentally induced lameness in horses.  They used eight horses in the study and over a four week period treated each with intravenous phenylbutazone, saline control, flunixin meglumine, or a combination of phenylbutazone+flunixin meglumine  at label dosages one hour after inducing lameness.  The horses were monitored for lameness score and heart rate for twelve hours after the lameness was produced. Blood samples for drug level were taken as well.  The results of the study showed that phenylbutazone alone decreased the lameness score the fastest; that all NSAID treatments decreased heart rate up to ten hours post treatment compared to the saline placebo; and that there was no difference between the flunixin meglumine and phenyulbutazone+flunixin meglumine groups through the entire twelve hours post treatment.  Another recent study showed that even just a few days of flunixin meglumine+half dose of phenylbutazone will cause gastric ulceration.

    The take home message is that only one NSAID is needed to treat lameness and that combining more than one will not improve the lameness any more than either drug alone, but you do greatly increase the risk for GI or kidney damage.

    What are the rules regarding NSAID use in competition?

    Horse owners need to be aware that using NSAIDs in combination is now forbidden under United States Equestrian Federation (USEF) regulations.  A rule change that went into effect December 2011 states that horses competing in USEF sanctioned events may use only one NSAID while competing.  If a horse is found to have more than one NSAID in their blood, disciplinary action will be taken.  This rule change was made to protect the welfare of the horse.

    There are certain situations where a second NSAID may be called for.  For instance, a horse who receives bute prior to competing that then incurs a minor corneal ulcer,  Flunixin meglumine could be administered in this case.  If the horse were fit enough to show, paperwork could be filed with the show steward and the horse allowed to compete.  These are very specific instances, and the welfare of the horse should be of utmost importance.

    All NSAIDs are forbidden under Fédération Equestre Internationale (FEI) regulations.

    The science is in; more is not better! If your horse requires an NSAID, please follow the dosing instructions carefully and do not combine NSAIDs.  The result will not be a sounder horse, but you may end up with a horse with serious, even fatal, side effects.  We all want to make our horses more comfortable, let's just not over do it.  

    Registered 2012 Equestrian Collections; Author: Sallie S. Hyman, VMD, DACVIM, CVA  

    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional.  In particular, all horse owners should seek advice  and treatment from a licensed veterinarian for their horses' medical care.  

    Please check with your show associations for any rules or regulations regarding drug usage.  This article is for informational purposes only, and should not be considered an authoritative document on drug usage during competition.

  • Equine Internal Parasites

    Equine Internal Parasites

    A parasite is an organism that lives on or in an organism of another species, known as the host, from which the parasite  obtains nutriment.  (Yuck!) Internal parasites of horses, therefore, live within the bodies of our horses and grow, feed, and reproduce there.  Although there are a number of internal parasites, worms are the ones most horse owners think of when parasites are mentioned.  We'll focus on the different types of worms that infect our horses and how to treat for them and to control their numbers in the environment.

    As the name implies, parasites gain their nutrition from their hosts and give nothing in return.  However, it is in their best interest not to kill their food source.  Horse in the wild live a nomadic, grazing lifestyle, covering large areas in search of food.  These horses carry a small worm burden, but their exposure is relatively low due to their constant movement that keeps the worm egg population low in any given area. Domestic horses, on the other hand, often carry very high, potentially health and life threatening worm burdens, due to high exposure and reinfection from confinement on small areas of pasture. 

    Each parasite has a specific life cycle, but in general they follow a similar pattern.  Eggs or larvae are passed in the manure and contaminate the environment. Horses grazing in that environment ingest the egg or larvae.  The larvae develop and mature in the digestive tract (stomach or intestines).  Some larvae migrate to other internal organs such as the lungs and blood vessels and can cause damage there, before returning to the intestines as mature adults to lay eggs.  The adult worms lay eggs that are passed out in the manure (or develop into larvae that are passed) to start the cycle again.

    What are the signs of parasites?

    Clinical signs of worm parasitism generally include weight loss, anemia, poor growth in younger horses, colic, diarrhea, poor hair coats, and death.  Many horse owners are familiar with the typical  pot-bellied, dull coated worm infested horse.  Although this clinical picture may be easy to recognize, most infected horses will have much subtler signs even with serious infections that can result in death. It is very important to do a fecal egg count on your horse.  A fecal egg count is more informative than a simple fecal floatation.  This will tell you whether your horse is carrying any internal parasites, how many, and how effective your deworming program is.  A fecal flotation test to detect eggs will not detect most tapeworm infections, however.   A blood test to determine exposure has been used to determine the prevalence of tapeworm infections in horse in the U.S.  Horses on the Pacific coast have the lowest prevalence at just 12%.  East coast horse have an infection rate of 60%, and those in the Mid-west have a 95% infection rate. 

    What types of worms are common in horses? 

    The most common and important worms that affect equine health are:
    • Ascarids (roundworms)
    • Large strongyles
    • Small strongyles (cyathostomes)
    • Tapeworms
    • Bots (Gasterophilus)

    Less common and usually less threatening worms are:
    • Lungworms
    • Pinworms
    • Stomach worms
    • Thread worms

    Roundworms (Ascarids) - Parascuaris equorum or roundworms usually infect young horses age 3-15 months.  Adult horses acquire a fairly strong immunity to ascarids.  These worms have an unusual life cycle that involves the larvae migrating through various internal organs (causing damage as they travel) until they reach the lungs.  The larvae are then coughed up into the horse's mouth where they are swallowed and continue their life cycle in the digestive tract.  Mature round worms can be several inches long and as thick as a pencil. These worms can cause an impaction of the intestines or stomach when found in large numbers.  Caution should taken when deworming a heavily parasitized horse, as the dying roundworms can also cause an impaction.  Consult your veterinarian if you suspect your horse has a heavy roundworm infection.  Broodmares should be dewormed thirty days prior to and /or at foaling to help decrease the foal's exposure. 

    Bots - Gasterophilus spp affect horses age two months and older.  Horses may develop mouth ulcers where the eggs burrow in after entering the mouth.  Some horses can develop stomach ulcers where the bots attach.  Sensitive horses may have a decrease in performance due to the ulcers.  Good grooming to remove the eggs from your horses legs will help to reduce their exposure, as will a targeted ivermectin treatment that is very effective in killing bots.

    Large Strongyles - Strongylus edentates, Stongylus vularis.  Both the larval and adult stages of the large strongyles cause damage.  The larvae migrate through the vessels of the intestinal mesentery and can cause thrombi (clots), infarctions, or inflammation of the vessels that, in turn, result in damage to the intestine.  The adults are plug feeders, that is they take bites of the intestinal lining that results in anemia and decreased absorption of nutrients.  Fortunately, these worms are susceptible to most dewormers. 

    Small Strongyles - Referred to as the cyathostomes, the larvae of this group are of the most importance.  The larvae burrow in to the intestinal lining  and become encysted for several months before completing their life cycle.  During this time, the larvae are resistant to deworming.  The intestinal mucosa is damaged when the larvae burrow in, especially when large numbers are present.  Horse exhibit signs of weight loss, poor hair condition, lethargy, poor growth, and colic.  Adult worm infestations also cause similar signs. Before and after they become encysted they are susceptible to most dewormers.   

    Tapeworms - Anapolcephala perfoliata, Anophlocphla magna.  Tapewoms were once thought not to be of much significance in horses, with a few exceptions in foals.  Recent research has shown that large number of horses are infected.  Tapeworms have an affinity for attaching at the ileum and ileocecal juction.  This can lead to inflammation and ulceration, which impares normal intestinal function.  This intenstinal malfuction can lead to three common types of colic - ileocecal intussusception, ileocecal  impaction, and spasmodic colic.  Fortunately, praziquantel has recently been approved for the treatment of tapewoms in horses and is very effective. 

    The following worms are less of a threat to your horse's health, but should be taken seriously and considered in your prophylactic deworming program or when a problem arises.

    Pinworms - Oxyuris equi lay their eggs around the horse's anus resulting in persistent itching and tail rubbing.

  • Equine Endurance and Electrolytes

    Equine Endurance Athletes and Electrolytes


    Endurance riding is increasing in popularity every year. The sport offers opportunities for just about every level of competitor, from the rider who likes to enjoy the trail, those seeking to find their personal best, and those who aim for first place.


    What is and Endurance Ride?


     Endurance rides typically range from 25-100 miles. Rides less than 50 miles long are called limited distance rides and are a fast growing segment of endurance riding. Rides are divided into divisions based on the weight of the rider for adults and an open division for junior riders 16 years old and under. Competitions are sanctioned by the American Endurance Ride Conference (AERC). Horse Welfare is paramount to the AERC. They have established strict veterinary checks at the start of and throughout the ride in order to ensure that all horses are fit and able to continue. Many studies have been conducted on endurance horses in order to determine what happens to them physiologically during extreme distances and what we can do in order to keep them healthy and safe.


    What happens to the horse during an Endurance Ride?


    One of the most noticeable things that occurs when horses exercise and especially when they exercise for a long period, is that they sweat. Sweating is designed to help cool the body from the tremendous amount of heat that is produced during work. As the sweat evaporates from the skin, it causes a decrease in temperature. Equine sweat is made from not only water, but also the electrolytes sodium, chloride, calcium, potassium, and magnesium, and proteins. The proteins are what make horses “lather”. As a horse becomes more fit, the amount of protein loss decreases. Unfortunately, this does not happen with the electrolytes. There is a negligible decrease in the amount of sodium lost as a horse gets fitter, but a fit horse loses about the same amount of sodium as a fat horse. And horses lose a lot of electrolytes in their sweat, much more than humans do. In fact, their sweat is hypertonic, that is, it has more electrolytes in it than does their blood. 


    We often say “Boy, I am sweating like a pig!” but we really should be “I am sweating like a horse”. Horses lose up to 5-7 liters of sweat per hour in cool temperatures and can lose up to 10-12 liters of sweat/hour in hot, humid conditions. An average 1000 lb. horse normally consume between 40-50 liters per day. In hot weather, he can lose all of that water intake in just a few hours of exercise.


    So why is the loss of water and electrolytes in sweat so important?


     Water loss will decrease the plasma (water) component of the blood, which in turn causes a decrease in blood volume and blood pressure. This can lead to decreased perfusion of the tissues and organs of the body. As a result of the decrease in blood volume, the heart will have to work harder and faster to pump the smaller volume of blood throughout the body in order to maintain proper oxygen levels. Dehydration then starts a competition for fluid between the cardiovascular system and the thermoregulatory system. When fluids are trying to be conserved for blood volume there is a decrease in blood flow to the skin and a decrease in sweat and evaporative cooling. Hyperthermia and hypovolemia can become severe and occasionally fatal.


     The loss of electrolytes can cause a whole host of disturbances in the body. Electrolytes help in many of the homeostatic processes within the body, including maintaining proper nerve conduction, proper muscle contraction and relaxation, maintaining normal body pH, and regulating body temperature. Loss of electrolytes can affect muscle cells and cause cramps and tying up. Cardiac muscle can also be affected and result in cardiac dysrhythmias (irregular heart rhythms). The smooth muscle of the gastrointestinal tract can be affected and result in colic. One unusual condition associated with electrolyte loss is synchronous diaphragmatic flutter, commonly called “thumps”. Chloride loss in sweat can cause metabolic alkalosis, an increase in the blood pH. This in turn causes an increase in the protein binding of ionized calcium in the blood. Ionized calcium is needed for nerve function. When it is decreased due to increased calcium binding nerve irritability increases. The phrenic nerve runs from its origin from the spinal cord at C3-5 and passes through the chest (near the heart) and then innervates the diaphragm. When the phrenic nerve is irritated due to low ionized calcium and then gets stimulated by the beating of the heart muscle, it will fire with each heart beat, causing the muscle of the diaphragm to contract. We see this as the “thump” of the diaphragm. 


     Exhausted horse syndrome is one of the most dangerous consequences of electrolyte and water losses. This occurs in horses that are exercised beyond their fitness level or in environmental conditions (hot, humid) that prohibit proper cooling and discourage water intake.  Clinical signs include elevated temperature, pulse, and respiratory rate; depression; anorexia; unwillingness to continue to exercise; dehydration; weakness; stiffness; hypovolemic shock; exertional myopathy; synchronous diaphragmatic flutter; atrial fibrillation; diarrhea; colic; and laminitis.


    Treatment includes stopping exercise; rapid cooling; rapid large volume intravenous or oral fluid administration; and nonsteroidal anti-inflammatory drug administration. Occasionally, death can ensue. Some horses show obvious signs of problems, such as collapse, unwillingness or inability to move, or outright colic. Others may be on the cusp of a metabolic problem but are not showing signs yet. 


    How is a horse with a potential problem identified?


    Veterinarians have developed the Cardiac Recovery Index to help identity these horses. This is an evaluation of the horse’s metabolic status. The horse’s resting heart rate is taken. He is then trotted 125 feet out and back. The pulse is taken again exactly one minute from the beginning of the trot. Failure of the heart rate to recover to or below the original value indicates potential problems. This horse should be carefully monitored so that treatment, if necessary, can be instituted as quickly as needed. As you can see, there is a complicated and delicate of balance between electrolyte levels and normal bodily functions. 


    How can we avoid these issues?


    Studies have been conducted to understand the effects of exercise and environmental conditions on electrolyte levels and hydration in horses. The 1996 Olympic Games in Atlanta were the impetus for many of these studies. Equine veterinarians were concerned about what toll the hot, humid temperatures of summer in the Southeastern U.S. would have on the equine athletes. These studies sparked many others that have helped all horses involved in endurance sports. Drs McCutcheon, Geor, conducted a study that showed that training or competing in hot, humid conditions caused losses in sodium, chloride, and potassium in sweat that exceeded the daily dietary intake of these electrolytes. This suggests the need for appropriate supplementation.


    So it would seem that the answer during an endurance ride would be to make your horse drink more water and give him electrolytes. But it is not that simple. It has been found that horses don’t always drink well after exercise. This is due to heavy breathing, their relatively small stomach size, and a blunted thirst response. Once a horse takes a drink and fills his stomach, he will not drink anymore until his stomach empties. Thirst is driven by a decrease in blood water volume and an increase in blood electrolyte concentration. Horses lose their thirst drive when they sweat excessively because they lose so much electrolytes in the sweat, thus there is no increase in blood levels to stimulate drinking. Dr. Harold Schott or Michigan State University found that giving a horse electrolyte water (0.9% sodium chloride) immediately after exercise will stimulate later thirst in the next hour post exercise. This will improve electrolyte levels and help to hydrate a horse better than giving plain water. The water should also be at ambient temperature. Horses preferred this to either warm or cold water. This brings up the old wives tale about not letting a hot horse drink. There is no science to support that allowing a horse to drink after exercise causes colic, laminitis, or any other problems. More likely, withholding water will result in these problems. 


    One caveat that was found during these studies was that it is not a good idea to give a horse electrolyte pastes prior to or during exercise if you know that he will not drink. If your horse ingests large amounts of electrolytes without proper water intake, he can develop a whole host of metabolic disturbances due to too high levels in the blood. Dehydration will also be exacerbated. 


    Electrolytes are essential for life. It is important to know how they affect the systems of the body and what can happen if there are disturbances in their levels. Knowing when and how to supplement electrolytes for the endurance horse can help to make the finish line an easier place to reach.


  • Burn Injuries

    Fire Related Injuries in Horses

    The recent high profile barn fire at True Prospect Farm in Pennsylvania that killed six horses and injured Boyd Martin’s Olympic alternate Neville Bardos and the terrible wild fires plaguing Colorado that have displaced hundreds of horses remind us of the dangers of fire and the severe and often fatal injuries that it can cause. It takes only 2-3 minutes for straw in a stall to ignite and burn a 10x10 foot area, burning at temperatures of 300 degrees. Thermal injury to a horse will occur when they are within 6 feet of that fire in their stall.

    Horses exposed to fire usually sustain two types of related, yet separate injuries. The first is burns. The second is smoke inhalation. The extent of injury dictates treatment and prognosis. Superficial burns are easily treated and not very expensive to manage. Serious burns can result in burn shock and hypovolemia, require aggressive and extensive treatment, and can be very expensive to manage. Burns of 50% or more of the body are almost always fatal, although burn depth can affect the prognosis. Horses that survive and heal from extensive burn wounds may have scarring that prevents them from returning to normal function. Inhalation injury can cause damage to the lungs that affects performance.


    Burns are classified by depth. 

    First-degree burns affect the superficial layers of the epidermis. These burns are painful, red, and edematous. The germinal layer of the epidermis is spared so the skin heals without complications.

    Second-degree burns involve the epidermis and can be superficial or deep. Superficial second-degree burns are painful, minimally affect the basal layer of the epidermis, and usually heal with minimal scarring in 14-17 days. Deep second-degree burns involve all layers of the epidermis. There is minimal pain, as nerve endings are also involved. An eschar (slough produced by thermal injury) forms over the wound. These burns can heal spontaneously, but usually with a lot of scarring. Skin grafts are recommended for optimal results.

    Third-degree burns involve the epidermal and dermal layers of the skin as well as the adnexal structures (hair follicles, sweat glands, sebaceous glands, nerve endings). The wound can appear from black to white in color. There is a noticeable lack of pain. These burns can result in fluid losses, shock, wound infections, and possible septicemia. They heal by contraction from the wound margin (like other full thickness wounds) and usually require skin grafts for optimal results.

    Fourth-degree burns involve all of the skin, underlying muscle, bone, fat, and fascia. The prognosis for fourth-degree wounds is poor.

    Horses can also sustain corneal burns and damage particulates in the air. Loss of vision is possible.

    Inhalation Injury

    The respiratory system is particularly susceptible to injury in fire situations. The delicate tissues of the entire respiratory tract from the nostrils to the lungs can be affected. Inhalation consists of three components: direct thermal injury; carbon monoxide poisoning; and chemical insult.

    Direct thermal insult causes edema and upper airway obstruction. The lungs are usually spared from thermal injury, as the superheated air is cooled due to the normal heat exchange mechanisms in the oropharynx and pharynx. The air is cooled before it reaches the lungs. Thermal injury can also cause damage to tissues of the trachea that can later slough and cause a tissue “plug” that obstructs the airway.  Carbon monoxide poisoning decreases oxygen levels available to tissues. It has a 230-times greater binding affinity for hemoglobin (the molecule that delivers oxygen to tissues) than does oxygen. This carboxyhemoglobin is unable to deliver oxygen to the tissues. Carbon monoxide also binds myoglobin, thus preventing oxygen delivery to muscle tissue. 

    Chemical insult depends on the materials that are burning. Pressure treated lumber contains hazardous chemicals, cleaning products, paints, pesticides, herbicides and many other substances can become dangerous when burned. Many of these products can turn into cyanide gasses, aldehydes, hypochloric acid or sulfuric acid. All of these are incredibly irritating to the respiratory tract. Some can even cause sloughing, edema, bronchoconstriction, decreased bacterial clearance, and decreased mucociliary clearance.

    Secondary pulmonary infections are very frequent after inhalation injuries due to the compromise of the clearance mechanisms of the respiratory tract. 

    Burn Shock

    After severe burns there is a dramatic cardiovascular effect called burn shock. It is similar to hypovolemic shock and can actually progress to hypovolemia. Heat causes capillaries to leak fluid. Tissue injury also causes chemical factors such as cytokines, nitric oxide, and oxygen radicals that also cause the capillaries to leak. The cycle is perpetuated when damaged vessels exacerbate tissue injury when they become clogged with cellular debris and leak fluid.

    Treatment of Burn Wounds and Inhalation Injury

    Treatment depends on the severity of the injuries. Initial examination should focus on stabilizing and maintaining a patent airway and treating/preventing hypovolemic shock. If severe upper airway edema is present, a tracheostomy may be necessary. Rapid fluid replacement should be initiated, but caution is necessary to prevent pulmonary edema. Massive amounts of protein can be lost through burn wounds and can result in fluid shifts into the lungs when large amounts of crystalloid (water-like) fluids are administered. Plasma and other colloidal fluids such as hypertonic saline or hetastarch may be necessary. Electrolytes should be monitored and replaced as necessary. Initially there is usually a hyperkalemia (high potassium) due to release from damaged cells, but hypokalemia (low potassium) usually ensues in 2-3 days. Intranasal oxygen may be needed to combat carbon monoxide poisoning or low oxygen levels due to anemia from burn induced intravascular hemolysis.

    Flunixin meglumine (Banamine) will help with discomfort and inflammation, but some horses will require srtonger pain relief with opiates. Free radical scavengers can be administered to combat oxygen radicals released from damaged tissues. Superficial wounds are cleaned and debrided and covered with a topical antimicrobial ointment such as silver sulfadiazine. Deeper wounds with blisters or eschar are left for 2-3 days to allow for any continued tissue death and are then treated. Systemic antibiotics are not usually effective for burn wounds and are used for inhalation injury only when there is clear evidence of infection. Corneal damage is treated with topical antimicrobials if not too severe, but may require corneal grafts if severe.

    Adequate nutrition is an essential part of healing from burn wounds. Burn victims become hypermetabolic to produce heat. A lot of heat is lost through evaporation of fluids lost through wounds. Protein is also lost in these fluids. Caloric expenditure and protein catabolism are greater in burn injuries than in any other injury. Accurate weight measurements should be made on a daily basis and nutrition adjusted if losses are noted. If a horse has severe burns to the muzzle, oral cavity,

  • West Nile

    West Nile Virus


    West Nile Virus (WNV) has been back in the news this year due to the resurgence in the number of human and horse cases being reported. As of the first week of September 2012, there were 1,993 human cases with 87 fatalities and 187 equine cases reported. Thirty-three states have confirmed cases of the virus.

    What is West Nile Virus?

    Once found only in Italy and Israel, West Nile Virus was first diagnosed in the United States in 1999. The first cases occurred in New York and Pennsylvania and it wasn’t long before the virus spread across the country. 

    The virus is a mosquito-borne disease that causes encephalitis (inflammation of the brain) and or meningitis (inflammation of the lining of the brain and spinal cord). The common house mosquito, Culex pipiens, is the species most commonly infected. Birds play a critical role as a reservoir for the virus. The impact of the disease in birds varies, with American crows frequently dying from the infection. Many other bird species survive infection with mild or no indication of disease. The birds can then pass the virus onto a mosquito that bites them. After the mosquito picks up the virus it takes 10-14 days for it to reach the mosquito’s salivary glands. Once in the salivary glands, the mosquito can transmit West Nile Virus to people, horses, or birds that it feeds on. West Nile Virus can also be transmitted via blood transfusion, through breast milk, and from mother to child (mare to foal) during pregnancy. Horses have not been shown to be able to transmit WNV to humans.

    What are West Nile Symptoms?

    Infection with West Nile Virus does not always lead to signs of illness in people or animals. In people, mild infections may be common and include fever, headache, and body aches, often with a skin rash and swollen lymph glands. In those susceptible to disease, signs can be severe and may include headache, high fever, weakness, neck stiffness, stupor, disorientation, coma, tremors, convulsions, paralysis, and possibly death.

    Horses appear to be a species that is susceptible to illness after infection with the virus. Severity of the disease varies from horse to horse ranging from mild illness to neurological signs to death.

    Clinically ill horses may exhibit the following signs:

    • Fever
    • Weakness of the hind limbs
    • Paralysis of the hind limbs
    • Ataxia (weakness)
    • Down, trouble getting up
    • Head pressing
    • Inability to swallow
    • Convulsions
    • Coma
    • Hyperexcitability
    • Depression
    • Loss of Appetite
    • Aimless wandering
    • Circling
    • Bowing

    Not all horses with these signs have West Nile Virus. There are other neurological diseases that present with similar signs. It is imperative to have a horse with any of these signs examined by a veterinarian and have proper testing done.

    How Do We Test for West Nile?

    Diagnosis of WNV infection in horses involves testing the blood serum for antibodies. Horses vaccinated for WNV and foals of positive-testing mares are likely to have a positive blood test for the virus. Veterinarians consider blood test results, clinical symptoms and the possibility of other neurological diseases, including rabies, Eastern Equine Encephalitis (EEE), Western Equine Encephalitis (WEE), Equine Rhinopneumonitis (equine herpes virus type 1), and Equine Protozoal Myeloencephalitis (EPM), before making a diagnosis.

    What is the Treatment for West Nile?

    Treatment for clinically ill horses is mostly supportive. Anti-inflammatory medications are used to reduce the inflammation. Plasma containing WNV antibodies can be administered to provide passive immunity to aid in treatment. Other supportive treatments would include keeping the horse in a safe, well padded stall, using a head bumper is necessary, and administering IV fluids and nutrition. Treatment will not guarantee improvement or survival. One third of infected horses will die or need to be euthanized due to the severity of their signs. 

    How Can We Prevent West Nile?

    The best way to protect your horse from WNV is to vaccinate and to eliminate mosquito habitats. Vaccination is very safe and effective. No vaccine is 100% effective, but when administered according to manufacturer recommendations, the vaccine is very good at preventing disease. As important as vaccination is keeping mosquitos away. Eliminate all sources of standing water around your farm. Old tires are a favorite breeding ground for mosquitos, so make sure they are removed. Mosquitos can breed in any puddle that is around for 4 days, so think of where water pools and try to eliminate those areas. Where possible, also try to discourage birds from coming into the barn. If you notice any dead birds, report them to your department of health. Do NOT touch them with bare hands. Other means of deterring mosquitos include stall fans, barn fly spray system, and fly sprays for your horse.


    Registered 2012 Equestrian Collections; Author: Sallie S. Hyman, VMD, DACVIM, CVA

    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional. In particular, all horse owners should seek advice and treatment from a licensed veterinarian for their horses' medical care.

  • Cold Weather Care

    Equine Cold Weather Care


    Dropping temperatures bring many challenges when it comes to caring for our horses during the winter. Being prepared and having a plan can help to keep our horses healthy and fit during these cold months.



    Water is one of the most important elements needed to help keep a horse healthy when temperatures drop. We typically think of horses needing water when they are hot and need to be cooled off, but water is equally as important when they are cold. Water is essential for regulating body temperature, whether the outside temperature is hot or cold. 


    Horses will tend to decrease water consumption as the temperature of the air, and their water, drops. Keep water buckets and troughs free from ice. Heaters are the most convenient way to accomplish this, but if you do not have power near your water troughs, you can add warm water to buckets and troughs to keep the water from freezing too quickly. Several studies have shown that warming water to at least 60° F will increase water consumption to 40-100%. Water should be maintained between 45 and 65 degrees F and any ice crystals should be removed. Horses normally drink between between 8 to 12 gallons of water a day, so make sure that a least this amount of ice free water is available.



    Hay is also essential to good health during cold weather, much more so than grain. Hay digestion acts as an “internal furnace” for the horse. Fiber is utilized through bacterial fermentation within the cecum and large intestine. Much more heat is produced in bacterial fiber fermentation than in digestion and absorption of nutrients within the small intestine (cereal grains). This results in a greater amount of heat being produced through the utilization of forages than utilization of grain. Feed as much hay as your horse will eat without wasting any.


    Grain may be necessary to help keep weight on hard keepers. 


    Dr. Kathy Anderson of the Nebraska Cooperative Extension has written on the “critical temperature”, that temperature at which heat production must increase and its effects on energy requirements:


    The critical temperature can be used to estimate changes in a horse’s nutritional requirement relative to falling temperatures, cold winds, and wet hair coats. Estimates for the lower critical temperature for horses are between 30 and 50 degrees Fahrenheit depending on hair coat, body condition, wetness and windchill. The critical temperature for cattle ranges from 18 degrees F for dry weather and heavy hair coats to 59 degrees F for animals with summer or wet hair coats. Estimates for the lower critical temperatures for horses are given in Table I.

    Table 1. Estimated Lower Critical Temperature for Horses in Moderate Body Condition

    Hair Coat

    Lower Critical Temperature (F)

    Wet or short






    For each decrease in coldness of one degree Fahrenheit below the critical temperature, there is an increase indigestible energy requirements of one percent for body temperature maintenance (Table II). The best estimate of coldness is windchill temperature, as this combines the effect of temperature and wind. For example a horse with a heavy winter hair coat has an estimated critical temperature of 30 degrees F (Table I). Thus, if the wind chill is 20 degrees F, the horse would have an increased energy requirement of 10 percent or 2 Mcal/day and should consume approximately two additional lb of hay per day (Table II). This 1,000 lb horse should already be consuming approximately 15 lb of hay per day, and now should consume 17 lb of hay to avoid any loss of body condition. Wet weather combined with wind greatly increases a horse’s energy needs (Table III). A horse in 32 degree F weather, without shelter and subjected to rain and 10 to 15 mph wind, would need to consume an additional 10 to 14 Mcal per day or a total of at least 25 lb of feed. Some horses would not be able to consume this volume of feed in hay alone.

    Table II. Estimated Feed Energy Increase at Different Magnitudes of Cold Below the Lower Critical Temperature of Mature Horses

    Difference in F Below Critical Temperature

    Digestible Energy  Increase (Mcals/days)

    Feed Intake Increase1(lb/day)
















    ¹Assuming an energy density of 1.0 Mcal/lb, which is typical of many hays.



    Table III. Effect of Wind and Rain on Digest Energy Requirement for Horses at Maintenance

    Average Temperature

    Additional Mcal/day

    Additional Hay

    32 degrees F

    10 – 15 mph wind

    4–8 Mcal/day

    4–8 lbs/day

    32 degrees F


    6 Mcal/day

    6 lb/day

    32 degrees F

    rain and wind

    10–14 Mcal/day*

    10–14 lb/day

    *May not be able to consume enough hay to meet requirements.


    Making sure your horse goes into the winter in good condition will help to minimize the increased energy demands of the cold weather. Some owners will even precondition their horses for the cold by increasing calories before the demand increases and allowing their horses to gain a little weight before winter.


    Long Hair vs. Blankets

    Horses grow a long thick coat as the daylight decreases. A natural haircoat is the best defense against cold weather. Warm air is trapped next to the skin when the hairs stand up in response to cold weather. This acts as a great insulator. Blankets are usually only necessary for clipped horses, geriatric horses, and for others when the wind is especially strong or there is rain. 


    Inside or Outside

    Although many horse owners immediately feel the need to put their horse in a stall when the temperature drops, most horses do not need to be stabled. Horses out at pasture do very well in colder temperatures as long as they have some sort of shelter or windbreak available to them. This will allow them to get out of the wind and rain/snow. If you do stable your horse, make sure that there is adequate ventilation. A tightly closed up barn will quickly become too warm for most horses and airborne dust, mold, and endotoxins can hurt your horse’s respiratory system.


    Hoof Care

    Don’t neglect routine hoof care. Many owners choose to pull shoes when horses aren’t working as much during the winter. Hooves grow more slowly during the colder months, but do need routine trimming to keep them healthy. 



    It is not necessary to forgo riding in winter, but there are some tips you should know. Warm up slowly to loosen muscles and any arthritic joints. A quarter sheet can help to keep your horse a little warmer, especially on windy days. A slow warm up will also help your horse’s heart and lungs adjust to the cold. Extremely cold air can cause lung damage, so take care when the mercury dips really low. Make sure that you prepare your horses feet for riding on snow and ice. Snow pads and Borium on shoes can help to prevent slips and falls. Riding on very hard frozen surfaces can cause sole bruises or injure sensitive lamina. Try to find softer ground to protect your horse’s feet.


    Winter doesn’t have to stop us from enjoying our horses. Knowing how to manage the challenges the cold can present will help keep you and your horse safe and healthy throughout the winter season.


    Registered 2013 Equestrian Collections; Author: Sallie S. Hyman, VMD, DACVIM, CVA

    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional. In particular, all horse owners should seek advice and treatment from a licensed veterinarian for their horses' medical care.

  • Cold Weather Care for the Senior Horse

    Cold Weather Geriatric Horse Care


    Older horses are affected more by the cold weather than their younger companions. Many owners talk about getting their geriatric horse “through just one more winter.” With a little bit of knowledge and planning, your older horse can stay comfortable and healthy, and getting through winter doesn’t have to be an ordeal.

    Seasonal Check Up

    A pre-winter veterinary examination is a good way to start getting ready for the cold weather. This exam can be conducted at the same time that your veterinarian does fall shots if you do those later in the season. If not, it is money well spent to have your vet out to check you horse out and discuss any issues that might need to be addressed before and during the cold weather. 

    Your veterinarian can assess you horse’s weight and make specific recommendations for nutritional needs. Old and new conditions such as Cushing’s disease, arthritis, heart murmurs, or lung conditions like Heaves can be discovered and addressed before the cold weather makes them more difficult to deal with. Many conditions will increase your horse’s caloric needs, so knowing if your horse is affected before the cold arrives will help you to send him into the winter in better condition.

    Remember that it may be more difficult for an older horse to get around on frozen terrain due to arthritis, foot problems, or neurological disease. Anti-inflammatory drugs can help make achy joints feel a little better in the cold weather. Keep feet properly trimmed and pick them out regularly to prevent snowball formation. If your horse wears shoes, consider providing a little traction with borium. Make sure that food and water sources are easily accessible for horses with mobility issues. An often-overlooked condition in older horses is cataracts. The glare of the sun off of the snow can make it difficult for horses with cataracts to see. If your horse has cataracts, consider putting a dark fly mask on him to help reduce the glare. A thorough dental exam should also be performed at this time. Untreated dental issues will affect your horse’s ability to properly chew hay and grain.


    Water, water, water

    Just like with younger horses, it is critical to make sure that an older horse is drinking enough water during the colder winter months. Water is important for temperature regulation and also for helping digestion. Too little water consumption can result in impaction colic. Older horses who do not chew their grain or hay thoroughly may already be slightly more prone to digestive disturbances and too little water lead to impaction colic. Provide clean, warm, ice free water to your horse. If you are uncertain about the amount of water he is consuming, you can always add warm water to his grain. This will help to ensure a certain amount of daily water consumption.


    Feed for warmth

    Feed itself and the fat layer that results from it help to keep your horse warm. Within minutes of eating a meal, the horse’s digestive processes begin to generate heat and warm the body. Over time, calories that are not immediately used are stored as fat that acts as insulation against the cold. Older horses are usually leaner with less fat and thinner muscles. Adding to the problem of trying to get adequate calories into your horse is the fact that older horses don’t utilize calories as well as younger horses. It has been shown that older horses have a 5% decrease in their ability to digest fiber and a 15% lower ability to utilize protein. Making sure that they are consuming adequate calories to maintain what they have and have enough to keep warm is paramount to maintaining your horse’s weight in winter.

    Hay is the best way to produce heat. The process of breaking down hay takes a long time and creates more heat over a longer period. Feeding as much hay as a horse will consume without waste is the best way to help keep him warm. Most horses will consume 2% of their body weight in hay a day. For a 1000 lb horse that is 20 lbs of hay. In winter, you probably will need to increase that amount. It is amazing how much nutrition horses get from pasture during the warmer months and owners are often very surprised by how much hay is needed to make up the difference in winter. Providing hay at night will keep the “burning” process going, so try to make sure that there is some forage available then. 

    Many older horses have dental issues that don’t allow them to chew hay anymore. There are a variety of hay alternative for these horses such as soaked hay cubes and chopped, bagged hay products. These will not produce as much heat as regular hay, but will provide needed fiber and a good amount of “heat”.

    It is often necessary to supplement an older horse’s diet with grain. If your horse normally gets grain, you may need to increase the amount in winter. Older horses need these calories to stay warm and maintain body condition.

    Another important aspect to keep in mind is to make sure that older horses are able to eat without being disturbed. If they are out in a pasture setting, make sure that they are not being bullied away from their hay or grain. It may be necessary to find a way to feed them separately or to temporarily fence off a small area for them.


    Blankets and Shelter

    Harsh winds and cold rain can take their toll on older horses. Believe it or not, snow actually acts as an insulator, even when it lands inches deep on a horse’s back, so it is not a worry. Wet rain that mats down hair and cold winds that blow the warm layer of insulating air are what cause problems. Keeping you horse out of these elements will go a long way towards keeping him warm. If he lives out on pasture, make sure that there is some type of shelter available so he can get out of the wind and rain if he chooses. A three sided run-in shed that blocks the prevailing winds in the best option. Again, if he is in a herd situation, ensure that he is not being bullied out of the shelter and that conditions such as ice, snow, or mud don’t make it impossible for him to get to it. It may be necessary to shovel a path and put down straw, hay, gravel, or shavings to make it safe to walk on. Keep the run-in shed clean of manure so the horses don’t have to stand in it.

    The general rule about blankets for unclipped horses is that they don’t need them. Most older horses are an exception to the rule. An older horse in very good weight with no health issues probably does not need a blanket. Any older horse that is thin going into winter or has any health issues that may increase his caloric needs or decrease his ability to take in calories should be blanketed. It is safer to assume that he needs a blanket than to let him lose a lot of weight and realize he needed one sooner. If you are unsure if you horse needs a blanket, look for clues. If you see him shivering then he definitely needs a blanket. Shivering is the body’s way to generate heat my causing muscles contractions. This can produce heat for a limited period of time. It is effective, but short-lived and uses up a lot of calories. A shivering horse can drop an astounding amount of weight in a very short time.

    Blankets come in a number of styles and weights these days. It is a good idea to have a couple of different weights, one for moderate temperatures and one for very cold temperatures. You can also layer blankets according to how much warmth you think your horse needs. The key, however, is not to get your horse too warm. If they sweat under their blankets they will have a hard time drying off and will get chilled and might start shivering. This defeats the purpose of the blanket. The most important fact about a blanket is that it is entirely ineffective if it is wet through to the horse’s skin. Make sure your blankets are waterproof and/or have several blankets so you can change them as needed. An equally important fact about blankets if fit. Make sure that your horse’s blankets fit properly. An ill fitting blanket can cause severe rubs on withers and shoulders and belly and leg straps can get tangled and cause injuries. Inspect blankets every few days for fit and for any damage.

    It is also very important to take off your horse’s blanket regularly. You can check for any signs or rubs, skin disease, and weight loss. It is easy to not recognize weight loss if you never take the blanket off.

    Do also run your hands over your unblanketed horse regularly as well. A fluffy, thick hair coat can hide weight loss. It is better to discover weight loss early and be able to manage it, then it is to find a very thin, unhappy horse in the Spring.

    Older horses need a little extra care in the winter. Helping them to maintain weight and stay warm through proper feeding and blanketing, along with good veterinary care will help your older horse get through another winter.


    Registered 2013 Equestrian Collections; Author: Sallie S. Hyman, VMD, DACVIM, CVA

    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional. In particular, all horse owners should seek advice and treatment from a licensed veterinarian for their horses' medical care.



  • Equine Rhinitis Virus

    Equine Rhinitis Virus


    An Old Virus Takes on New Importance

    Recent outbreaks of respiratory disease in horses have led to the discovery of the emerging importance of Equine Rhinitis Virus as a cause of respiratory illness. Equine Influenza Virus and Equine Herpes Virus are the most common causes of equine respiratory illness, but more recently, Equine Rhinitis Virus has been implicated. This virus was once thought to be of little clinical significance, but we now know that it can cause serious illness.
    Equine Rhinitis Virus should not be confused with rhinopneumonitis, which is caused by Equine Herpes Virus. There are two forms of the Equine Rhinitis Virus (ERV), equine rhinitis A (ERAV) and equine rhinitis B (ERBV). Serologic studies show that ERV is distributed worldwide, with prevalence ranging from 20%-70% in countries including the United Kingdom, the United States, Canada, Australia, New Zealand, Germany, and Japan. 
    Horses have been documented to be infected with both influenza virus and ERV, suggesting that some outbreaks may be caused by both viruses.
    Since the virus has not been well studied, we do not know much about how it is transmitted. It is likely, however, that it is transmitted similarly to other respiratory viruses through direct contact with nasal secretions and aerosolized secretions when horses cough or sneeze. Secretions on fomites such as stall doors, buckets, troughs, etc., may also be sources of transmission.  

    What are the Clinical Signs?

    Clinically, horses present with typical signs of respiratory disease. These signs include:
    • Fever
    • Swollen painful submandibular lymph nodes
    • Seromucoid discharge that progressively becomes more mucoid
    • Ocular discharge
    • Dry cough
    • Occasionally lower leg swelling
    • Increase in respiratory rate and bronchial sounds
    • Anorexia

    How Can My Vet Diagnose ERV?

    Diagnosis is not easy, but relies on virus isolation, polymerase chain reaction (PCR) and serology. Most labs in the U.S. are not routinely testing for ERV and currently only two laboratories are set up to do so, so veterinarians are having to ask specifically for this virus to be included in testing. PCR is a relatively quick screening method, but it does not differentiate between dead virus that may be present after an infection is cleared, virus that is not causing clinical signs, or virus responsible for active infection. Paired serology, watching for a 4-fold increase in antibodies in blood samples taken at 10-24 days apart is confirmatory for the disease.

    What is the Treatment?

    Treatment is mostly symptomatic. Non-steroidal anti-inflammatories can decrease the fever and make the horse feel more comfortable. Antibiotics may be prescribed as well. The damage the virus causes to the upper and lower respiratory tract makes the horse more susceptible to secondary bacterial infections. Rest is critical and may be required for up to 21 days. Without rest, inflammation persists and makes the respiratory tract more sensitive to dust, mold, and other allergens and can result in lower airway inflammation or inflammatory airway disease. It takes the respiratory epithelium 21 days to repair after damage. Any exercise prior to this will cause prolonged inflammation that can affect a horse’s performance for the rest of its life. Rest can include turnout, which is preferred to get the horse out of the dusty, moldy environment of a stall.

    How can Horse Owners Prevent this Illness?

    Good hygiene practices are paramount to preventing ERV. Quarantine any new horses for 2 weeks to prevent introducing viruses to the rest of the barn. Make sure that any sick horses are also quarantined and that all buckets, shared cleaning utensils, etc., are disinfected. Handlers must wash hands after being with sick horses.
    There is now a vaccine available from Boerhringer-Ingelheim to protect against ERAV. You should speak with your veterinarian to see if this vaccine is right for your horse and your situation. 

    Registered 2013 Equestrian Collections; Author: Sallie S. Hyman, VMD, DACVIM, CVA

    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional. In particular, all horse owners should seek advice and treatment from a licensed veterinarian for their horses' medical care.

  • Equine Ulcers

    Equine Gastric Ulcers

    Equine Gastric Ulcer Syndrome (EGUS) is a common problem in horses of all ages and disciplines. Ulcers are wounds in the lining of the stomach caused by acid. Studies of various populations of horses have found the prevalence of EGUS to be quite high. 


    •             Discipline                    % of population affected
    •             Flat Racing                                          92

    •             Harness Racing                                   86

    •             Saddle Seat                                         82

    •             Reining                                                76

    •             Cutting                                                69

    •             Show jumping                                     67

    •             Eventing                                              62

    •             Barrel Racing                                      51

    •             Dressage                                             44

    Reports found that 25 to 50 percent of foals have ulcers.


    So why do so many horses have gastric ulcers? The short answer is how we manage them; how we feed them, how we train them, how we keep and transport them. 

    Horses evolved to be nomadic grazers. Their gastrointestinal (GI) tracts are designed to have fiber (grass, weeds, leaves) in them at all times. A horse’s stomach continuously secretes acid (mainly hydrochloric), whether there is food in it or not. An adult horse can produce up to 16 gallons of acidic fluid each day. In nature, horses are continuously grazing, so the stomach is rarely empty. This food in the stomach, along with bicarbonate in saliva, helps to neutralize the stomach acid. In addition, the movement of continuous walking promotes GI motility and keeps food and acid moving out of the stomach. Horses begin to secret stomach acid as young as two days of age and the acidity of their stomach secretions is usually very high. In the adult horse, the pH of gastric contents ranges from 1.5 to 7.0, depending on region measured. A near neutral pH can be found in the dorsal portion of the esophageal region (saccus cecus) near the lower esophageal sphincter, whereas, more acidic pHs can be found near the margo plicatus (3.0-6.0) and in the glandular region near the pylorus (1.5-4.0)


    Stomach anatomy

    The horse stomach is divided into two distinct regions, the esophageal or non-glandular region and the glandular region. The esophageal region or squamous mucosa covers approximately one-third of the equine stomach, is void of glands, and is covered by stratified squamous epithelium similar to the esophagus. The glandular region covers the remaining two-thirds of the stomach and contains glands that secrete hydrochloric acid, pepsin, bicarbonate and mucus.

    The glandular mucosa is protected from acid damage by proper blood flow, bicarbonate buffering of acid, and mucus that forms a protective layer over the mucosa. Ulcers can be present in either the squamous or glandular portion of the stomach, but are more common in the squamous portion at the margo plicatus. This area is almost constantly exposed to acid, pepsin, bile acids and organic acids. Ulcers in the glandular mucosa are usually due to disruptions in blood flow to the area and decreased mucus and bicarbonate production.  


    Causes of EGUS

    EGUS is a complicated syndrome with many causative factors.

    Fasting or intermittent feeding have been shown to consistently induce gastric ulceration in horses. The empty stomach is exposed to acids which can attack the defenseless squamous mucosa and overwhelm the defenses of the glandular mucosa.

    Diets high in concentrates have also been shown to induce ulcers. The carbohydrate rich grains are fermented to volatile fatty acids (VFA). These VFA enter the cells of the squamous mucosa, cause the cells to swell and die, cause inflammation, eventually ulceration. 

    Exercise causes increased intra-abdominal pressure in horses resulting gastric compression, pushing acidic contents into the proximal, squamous-lined region of the stomach. Increased duration of acid exposure directly related to daily duration of exercise may be the reason that squamous lesions tend to develop or worsen when horses are in intensive training programs. Exercise may also have an inhibitory effect on gastric emptying.

    Anything that causes delayed gastric emptying will predispose a horse to gastric ulcers. This is most common in foals with duodenal outflow obstructions, but can occur in adults with ileus due to any number of conditions.

    In foals, gastric ulceration may be related to desquamation or “shedding” of the squamous epithelium of the stomach. Desquamation of the squamous mucosa, occurs in 80 percent of foals up to 35 days of age. In a study of rats, it was found that the loss of epithelial cells along the margo plicatus resulted in the increased susceptibility of this region to acid injury. Also, acid injury to this region resulted in a delay in re-epithelialization. Delayed re-epithelialization could result in acid injury of the deeper layers from hydrochloric acid and lead to gastric ulceration.

    Housing, Trailering, Nsaids

    Horses that live outside and are allowed to graze at will have fewer ulcers than horses that are stalled. One study found that horses that were brought into stalls after living outside developed gastric ulcers, some in as little as 24 hours.

    Trailering horses causes stress that leads to gastric ulcers. An interesting fact found during this study was that not only did the horses who were transported during the study develop ulcers, but so did those horses who were left behind. Seems as though everyone got stressed. This stress can lead to increased cortisol levels, decreased blood flow to the stomach, and reduced hay intake, all of which contribute to gastric ulceration.

    Non-steroidal anti-inflammatory drugs are notorious for causing stomach ulcers in all species. They reduce protective prostaglandins, decrease mucus production, and interfere with proper blood flow to the stomach.

    Signs of EGUS

    Horses will display a variety of clinical signs in response to gastric ulcers. These can range from being off feed to knocking down rails in the jump off. Each horse will have a different tolerance and can make recognizing the signs difficult. Below is a list of some of the more typical signs associated with gastric ulcers.

    •  ·        A change in attitude - Is your horse more nervous than usual or less willing to perform? Does he seem grouchy or "out of it" for no apparent reason?

    • ·         Poor appetite - Is he eating as much as he normally does for the amount of work he's accomplishing? Is he leaving any of his feed uneaten? Does he start to eat his grain, then back away?

    • ·         Colic - Is your horse showing signs of low-grade colic, a persistent mild discomfort?

    • ·         Decreased performance - Is your horse not as "fluid" as normal? Could his usually fine movement be described as below average?

    • ·         A decline in body condition - Is your horse's coat not quite as sleek and shiny as it once was? Does he look "unthrifty" or just plain poor?

    • ·         Weight loss - Has your horse dropped weight, up to but not more than 10 percent of his body weight?

    • ·         Dull - Is your horse generally lackluster and seemingly without energy?


    Although the clinical signs of EGUS may be hard to recognize, diagnosis is quite simple. An endoscopic examination will reveal whether or not your horse has ulcers. The procedure is done under standing sedation on an outpatient basis. It is imperative that you follow your veterinarian’s recommendations and advice for fasting your horse prior to the procedure. If the stomach is full of food or water, there is no way to see whether or not there are ulcers. Some clinics prefer that you drop your horse off the night before so that they can ensure that he is properly fasted.

     Ulcers are graded on a zero to three basis. Grade Zero means there are no signs of ulceration.  Grade One means that there is a single to a few, small lesions present. Grade Two means multiple lesions up to medium sized are present. Grade Three means there are extensive, coalescing, deep ulcers, possibly bleeding, present.


    Treatment is aimed at healing the ulcers and reducing the factors that cause them. Several medications are available that effectively treat gastric ulcers by reducing gastric acid secretion. FDA approved omeprazole products such as Gastrogard and Ulcergard have been proven to heal ulcers. Omeprazole is a proton-pump inhibitor that turns off acid secretion. Omeprazole products are given once daily and are, therefore, very convenient. Type-2 histamine (H2) blockers such as ranitidine have also been effective in treating ulcers. Histamine is a naturally-occurring chemical that stimulates cells in the stomach (parietal cells) to produce acid. H2-blockers inhibit the action of histamine on the cells, thus reducing the production of acid by the stomach.

     Feeding calcium and protein rich alfalfa helps to buffer stomach acid. Reducing the amount of concentrate fed is also advised. Allowing as much access to pasture is also recommended.


    Today we know the factors that induce gastric ulcers. Knowledge is power and we know that we can help to prevent our horses from actually developing a full blown case of ulceration. Veterinarians recommend treating horses prophylactically during stressful times such as trailering for lessons, competitions, or relocating, or when other horses in your horse’s circle of friends leave.

     If a horse must be confined, ensure free choice access to hay and enrich the environment to reduce as much stress as possible. Provide toys (such as treat feeders), mirrors, and make sure he can interact or at least see his buddies.

    Gastric ulcers can negatively affect your horse’s performance and health. Knowing what factors can cause them and signs to look for will help you identify if your horse is at risk or may even have ulcers. 

    Registered 2013 Equestrian Collections; Author: Sallie S. Hyman, VMD, DACVIM, CVA

    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional. In particular, all horse owners should seek advice and treatment from a licensed veterinarian for their horses' medical care.

  • Rain Rot

    Rain Rot

    Every horse owner has experienced or knows someone whose horse has experienced Rain Rot. Those painful, oozing, crusty scabs that can seemingly appear overnight and seem to spread at the speed of light.

    What is Rain Rot?

    Dermatophilosis, more commonly referred to as “Rain Rot” is an infection of the epidermis of the skin by Dermatophilus congolensis.  D. congolensis is a gram positive, non-acid-fast anaerobic actinomycete. Actinomycetes are organisms with characteristics common to both bacteria and fungi but yet possessing distinctive features to delimit them into a distinct category. Like a bacteria, they are unicellular, but like fungi, they produce hyphae (long branching filaments).

    The natural habitat of D. congolensis is unknown, but as most actinomycetes are soil dwellers, it probably can reside there, although attempts to isolate it from soil have been unsuccessful to date. It has been recovered only from infected or carrier hosts and these are thought to be the main reservoir of the disease.

    The condition usually appears during wet, humid times of the year and often when horses are blanketed. The zoospores require moisture and warm temperatures in order to be released. Blankets help to provide a warm and moist environment over the horse’s skin, especially if the horse sweats under the blanket of the blanket does not get changed after it gets wet from rain or snow.

    In order for an infection to be established, there must be some break in the skin such as an abrasion, a bug bite or other breach of the protective barrier. Low concentrations of carbon dioxide emitted from the skin attract the motile zoospores to susceptible areas on the skin surface. Zoospores germinate to produce hyphae, which penetrate into the living epidermis and subsequently spread in all directions from the initial focus. Hyphal penetration causes an acute inflammatory reaction. This inflammatory reaction then culminates with the epidermis cornifying, separating, and forming the characteristic scab.

    The lesions usually start out with the hair matted together as “paint-brush” lesions, then progress to curst or scabs, and finally become accumulations of cutaneous keratinized wart-like lesions.  A thick yellow-green pus is usually present under the crusts. Lesions can occur anywhere on the body are most common over the dorsal surface (back), upper and lateral areas of the neck, face, and chest. White haired areas seem to be particulary susceptible.

    Dermatophilosis is seen in all age, sex, and breeds.  However, younger animals, those housed in very moist, humid conditions, and immunocompromised animals are more susceptible. Animals will display various degrees of pruritis (itchiness). Most affected animals recover spontaneously within 3 weeks of the initial infection (provided chronic maceration of the skin does not occur). In general, the onset of dry weather speeds healing. Uncomplicated skin lesions heal without scar formation. Lesions on the lower limbs can be painful enough to affect a horse’s performance. And certainly, if the lesions cover a large area of the body, especially over the back, it may not be possible to saddle your horse.

    Horses become infected through contact with carrier or overtly infected animals. Fomites such as blankets, brushes, saddle pads, and tack can also transmit the disease. Biting insects such as flies and ticks can also serve as vectors.

    Diagnosis is usually made based on clinical signs and the typical appearance of lesions. A smear of the crusts or pus can be made to identify D. congolensis. A definitive diagnosis is made by demonstrating the organism in cytologic preparations, isolation via culture, and/or via skin biopsy. An indirect fluorescent antibody technique and a single dilution ELISA test have been developed for large serologic and epidemiologic surveys. The most practical diagnostic test is cytologic examination of fresh crusts and/or impression smears of the underside of freshly avulsed lesions. Fresh crusts are minced on a glass microscope slide with a sterile scalpel blade in several drops of sterile saline.

    How Do I Treat Rain Rot?

    Horses are treated using topical antibacterial shampoos that contain chlorhexidine, povidine-iodine, or benzyl peroxide. The horse should be lathered up, the shampoo left to soak for 10 mintues and then rinsed.  Any loose scabs should be gently removed. Any adherent crusts can be treated with a povidine-iodine ointment to help to soften them for later removal. Severely affected horses may require parenteral antibiotics. However, these should be reserved for only the most severely affected and must be used in combination with topical treatments. Topical treatment with povidone-iodine has been found to be superior to parenteral oxytetracycline alone (100% to 66% effective, respectively).

    Affected horses should be isolated and all equipment that has been in contact with them should be disinfected. Crusts that are removed from horses should be disposed of in the trash and not thrown on the floor in order to prevent creating a source of reinfection. Preventing chronic maceration of the skin and keeping your horse dry are important. Make sure that wet blankets are removed and horses have shelter to get out of the rain if they choose.

    Finally, it is very important to keep in mind that dermatophilosis can be transmitted to humans. Contact with an infected animal can lead to infection on exposed skin of the handler.  You should wear gloves when handling infected animals and always thoroughly wash your hands with soap after contact with the horse or their equipment.
    Registered 2013 Equestrian Collections; Author: Sallie S. Hyman, VMD, DACVIM, CVA

    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional. In particular, all horse owners should seek advice and treatment from a licensed veterinarian for their horses' medical care.

  • Fall Hazards: Red Maple Leaf Toxicity

    The Fall season brings cooler weather and beautiful colored foliage. Leaves start to fall and the grass starts to die back. Although we may see this as a time to get off the mower and get on our horses to enjoy the beautiful scenery, it can be a very dangerous time for horses if the wrong things end up in there pasture.
    Red maple leaves and acorns from oak trees pose very serious threats to horses. Both are highly toxic and can cause serious harm and death if ingested. Horses often eat red maple leaves or acorns if there is not enough grass left in the pasture and they are not supplied with supplemental forage such as hay or hay cubes. Some horses accidentally taste acorns that have fallen into a field and then develop a taste for them and seek them out.

    Red Maple Leaf Toxicity

    The native red maple (Acer rubrum), also called swamp or soft maple, is a potent killer of horses and ponies. Red maple is a tree native to the eastern half of North America.


    The toxic ingredient in red maple leaves is believed to be gallic acid . Gallic acid causes methemoglobinemia and is found in the leaves of red maple, sugar maple and silver maple trees. Ingestion of wilted or partially dried red maple leaves from fallen or pruned branches causes lysis of the red blood cells with the subsequent development of a hemolytic anemia, which can be deadly. The problem can occur from June to October. Ingestion of dried or wilted, but not fresh, maple leaves is associated with the toxicosis. Although dried leaves may remain toxic for 4 weeks, they are not generally believed to retain toxicity the following spring. Older wilted leaves, e.g., those collected after September 15, cause faster poisoning than wilted leaves of early summer growth. This indicates that the amount of toxin increases in leaves during the summer. Red cell damage has been reproduced in horses ingesting 1.5 to 3 pounds of dried leaves per 1,000 pounds of body weight. Ingestion of fresh leaves does not appear to cause disease.

    Clinical Syndrome

    Horses often die within 18-24 hr of ingestion of wilted leaves. Horses that remain alive for 18-24 hr after ingestion of wilted leaves will be severely depressed and cyanotic and produce dark red or brown urine. The mucous membranes are blue to brown from poor oxygenation. They suffer intravascular and extravascular hemolysis (red blood cell breakdown). The percentage of red blood cells circulating in the blood (packed cell volume (PCV)) can drop as low as 8%-10% and the hemoglobin (Hb) concentration can be as low as 50 g/L. The normal PCV and Hb concentrations in horse blood are 28%-44% and 112-169 g/L respectively. Death is due to a severe lack of oxygen delivery to vital cells from hemolysis of red blood cells, anemia and the oxidation of hemoglobin to methemoglobin, which is incapable of transporting oxygen. The clinical signs observed in horses that eat red maple leaves include: colic, fever, followed by laminitis and disseminated intravascular coagulation.
    Blood changes of horses with red maple leaf toxicity include anemia, hemoglobinemia, Heinz body formation, increased AST, SDH, plasma protein, and bilirubin.


    Early treatment is aimed at preventing absorption of the toxin if the syndrome is recognized quickly, especially if the owner saw the horse eat leaves. Activated charcoal or mineral oil can be used to slow absorption. Activated charcoal will also bind some of the toxin. Once clinical signs have occurred, treatment is symptomatic and aimed at maintaining a viable PCV and oxygen level. IV fluids are used to help flush the products of red blood cell breakdown out of the kidneys and to prevent dehydration. Blood transfusions may be necessary if the PCV drops below 15%. Nasal oxygen supplementation can also be used to keep oxygen levels within normal limits. The condition also causes colic like symptoms and the pain can be carefully treated with non-steroidal anti-inflammatories or opiates as needed. 


    Prognosis is guarded to poor for horses who consume large amounts of wilted red maple leaves.

    Identifying Red Maples

    The leaves of red maples are palmate (like the palm of your hand), 5-15 cm long and about as wide, with 3 to 5 lobes. The two sides of the center lobe are almost parallel to the midvein (5). Between the lobes, the leaf edge or leaf margin is serrated or jagged, while the leaf margin of sugar maple and Norway maple is smooth with no serrations. The underside of the red maple leaf is silver grey and the keys are red. Red maple can hybridize with silver maple, creating crosses of intermediate forms that should also be avoided near horse pastures. Silver maple is a soft maple with heavily indented lobes compared to red maple or sugar maple. In northern parts of Ontario, mountain maple with its small, heavily serrated 3- to 5-lobed palmate leaves could be confused with red maple. However, it only grows to 3-5 m or as a shrub. Red maple trees can grow up to 25 m high. Researchers have identified the presence of gallic acid in silver and sugar maple as well as red maple. Although no reports citing either of them as a cause in poisoning have been published, there have been anecdotal reports of possible poisonings.


      Remove any limbs or leaves from red maple trees that have fallen into a pasture, looking after each rain or wind storm in particular. Trim trees near pastures so that horses are not able to reach the branches to eat leaves.

    Oak Leaf and Acorn Toxicity

      Poisoning can occur in Spring when young oak leaves are eaten, but it mostly occurs due to ingestion of the acorns in the Autumn. This is due to the tannic and gallic acids in the acorn, which can cause severe damage to the gastrointestinal system, liver, and kidneys.

     Clinical Signs

     If horses are eating acorns, the husks can often be seen in their droppings. Many horses are unaffected but clinical signs to look out for include depression, loss of appetite, mouth ulcers, abdominal pain (colic), constipation followed by diarrhea which may contain blood, blood in the urine, leg edema, weakness and incoordination.


    There is no specific antidote for acorn toxicity and treatment of these cases involves intravenous fluids to prevent dehydration and correct electrolyte abnormalities.  If horses develop kidney failure, intravenous fluids can help to increase blood flow to the kidney and furosemide can be used to increase urination.  Mineral oil or activated charcoal can be given orally to help remove the toxin from the gastrointestinal tract as soon as possible.  The prognosis for horses with acorn poisoning is guarded, so it is much better to prevent the problem than treat it. 


    The only way to prevent acorn poisoning is to prevent your horses from having any access to the oak trees and the acorns that fall from them. This will undoubtedly involve fencing off the trees and the area of ground where the acorns fall or alternatively picking up fallen acorns daily and remove low branches.
    Individual animals have different levels of tolerance. Therefore it is not possible to say how many can be eaten in a given period of time without causing symptoms, however small amounts do not usually cause problems. Acorns can become addictive; some horses will actively search for them once they have acquired the taste.
      Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional. In particular, all horse owners should seek advice and treatment from a licensed veterinarian for their horses' medical care.  

  • 2013 AAEP Convention

    2013 AAEP Convention Highlights


    This year’s American Association of Equine Practitioners’ Annual Convention in Nashville, Tennessee was like an early Christmas gift for equine practitioners and the clients and patients they are for. Held December 7-11th, nearly 150 topics, presented and researched by over 300 veterinarians, filled the 5 day convention.

     I will attempt to highlight as many topics as I was able to attend and will apologize in advance for not getting to cover every topic (which will also reveal my preferences for certain topics). There was just so much learn and not enough time in which to do it! 

     The convention opened with a motivational talk by Buck Brannaman. This man’s understanding of the equine mind, natural horsemanship, and outlook on life is inspirational. It was also refreshing to hear someone talk about how horsemanship, or the lack thereof, affects veterinarians and our safety. I highly recommend you check out anything you can find on Buck, if only for his wonderfully dry sense of cowboy humor.

     On day 2, Dr. Sue Dyson delivered the Frank J. Milne State-of-the-Art Lecture “Equine Lameness: Clinical Judgment Meets Advanced Diagnostic Imaging.” Her many years of work in the evaluation of lameness have given her unprecedented insight into equine lameness workup and imaging. The take home point of her talk was that we now have the ability to image a lot of structures that we may or may not be able to assign as the cause of lameness and even then, we may not have a way to treat them


    A group from Michigan State University College of Veterinary Medicine and the Maxwell Gluck Equine Research Center did a study on the effect of non-steroidal anti-inflammatory treatment at the time of vaccination. Many horse owners know that their horse will have an adverse reaction at the vaccination site or a systemic reaction such as fever, lethargy, and inappetence. Often, owners or veterinarians administer anti-inflammatories such as bute, banamine, or previcox prior to vaccination. The group found that this will decrease both the antibody response and the cellular immune response to vaccination (in this case, to influenza). Some horses will always need pretreatment, but it is good to know that their response may not be as strong, so adjustments can be may to keep them protected.


    Several new techniques and observations in lameness have been identified this year. A new technique for injecting the navicular bursa that avoids penetrating the deep digital flexor tendon has been described. A new basilar sesamoid approach for digital flexor tendon sheath in the horse was also described. This technique is very easy to perform and has a very high success rate.

     Long thought, but finally proven is the lack of specificity of many regional nerve blocks that are used to “block out” areas of lameness. Studies have shown that the analgesic substances used to perform blocks can travel quite a distance from where they are injected, thus causing analgesia to more structures than planned.

     Standardization of drug withdrawal times is a concern in the Thoroughbred racing world, so several studies were performed to establish the pharmacokinetics and clearance of triamcinolone acetonide and methylprednisolone acetate (drugs commonly used for joint injections). Both drugs were below detectable levels in plasma by day 8 after intra-articular injection.

     A novel treatment for subchondral cystic lesions in the medial femoral condyle (in the stifle) was presented. Horses with large cyst-like lesions of the stifle usually exhibit lameness and fail to become sound with many traditional treatments. 75% of horses treated by placing a transcondylar bone screw across the cyst returned to soundness and were able to work. Radiographic follow-up showed marked filling in of the cyst.


    A session on how to treat a horse with excessive tearing was very useful. Many owners know the frustration of owning a horse with drippy eyes. The most common causes of this problem are environmental irritants that should be managed with a fly mask and functional obstructions that can be caused by inflammation, foreign bodies, or stones in the tear duct. These blocked ducts need to be gently flushed. If the duct opens up, then systemic antibiotics and anti-inflammatories are indicated for 2-3 weeks. Severe cases may require surgery to restore tear flow.

     Standing enucleation is becoming more of the accepted norm rather than the exception these days. The procedure has been shown to be well tolerated in properly selected cases. Not all horses will be right for this procedure, but it is a good option for horses who are at risk under general anesthesia.

     Geriatric Medicine/Metabolics

    Cushing’s Disease or Pituitary Pars Intermedia Dysfunction (PPID) was the subject of several talks. Better diagnostic tests have become available that are allowing us to identify horses at a much early age and stage of the disease. A resting ACTH will identify those horses with moderate to severe disease, but a Thyrotropin Releasing Hormone stimulation test is useful in horses with suspected disease, but normal ACTH levels. Pergolide is still the mainstay of treatment.

    Equine Metabolic Syndrome (EMS) is defined as hyperinsulinemia, abnormal adiposity, abnormal response to oral glucose testing, a predisposition to laminitis, and high triglyerides. We also have a new diagnostic test to help identify at risk horses earlier. Resting (fasting) glucose and insulin levels again, will identify severely affected horses, but the oral sugar test is very good at catching early disease. This is an easy to perform test whereby the horse’s baseline insulin is measured and is then given an oral dose of Karo syrup. Additional insulin measurements are taken at 60 and 90 minutes later.  High levels are indicative of EMS. Dietary management is key in treating EMS. Refractive cases may require drugs such as metformin to help manage insulin levels.

    The line between PPID and EMS are not as clear as we once thought. Many horses with EMS will go on to develop PPID. Some horses can manifest both diseases at the same time.


    A study was conducted to evaluate the incidence of abortions in pregnant mares undergoing colic surgery. The group found that 70% of mares who underwent colic surgery went on to deliver a live foal, even in mares as old as 15 years. Pregnancy loss was usually in mares in early pregnancy (less than 40 days).

    Oviductal blockage can be a cause of infertility in mares. Direct application of prostaglandin to the oviduct may help these mares return to fertility, even after several years of infertility.

    Anti-Mullerian Hormone may be a better test for mare with granulosa cell tumors of the ovaries. It should be included in the graulosa cell tumor screen along with testosterone and inhibin.

     Internal Medicine

    The Skin Prick Test (SPT) was applied to horses to try to identify allergens that may be triggers for those with Reactive Airway Obstruction (RAO). All horses with RAO were positive to at least 5 allergens. Half of the healthy control horses had positive SPT to 1-3 allergens but with a much lesser degree of reactivity. The SPT may be a step toward determining which allergens are triggering RAO and may lead to specific immunotherapy.

    The ever controversial Lyme disease was the subject of a table topic where veterinarians were able to discuss their experiences with the disease. The multi-plex test from Cornell was considered the best diagnostic to date. With doxycycline not available or cost prohibitive, the treatments of choice are IV oxytetracycline or oral minocycline. No vaccines are approved for the horse, but many practitioners are using the canine vaccine off label in endemic areas.

    This is just a small sampling of the topics that were covered at the 2013 AAEP Convention. It was a great opportunity to meet with colleagues, share experiences, and learn the latest information on everythine equine. Ask your veterinarian what they learned! I am sure they will be happy to tell you.

    Registered 2013 Equestrian Collections; Author:  Sallie S. Hyman,  VMD, DACVIM, CVA 

    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional.  In particular, all horse owners should seek advice  and treatment from a licensed veterinarian for their horses' medical care.  




  • "Heaves" What is it?

    “Heaves”: Equine Recurrent Airway Obstruction


    Cold winter weather means that our horses may be spending more time inside. It is tempting to close up the barn to keep warm, but doing so can compromise the quality of the air. Poor ventilation can result in high levels of allergens from molds and endotoxins in the air. These substances can affect a horse’s respiratory system and cause Recurrent Airway Obstruction (RAO), also known as heaves. Heaves is a chronic, non-infectious airway condition of horses.


    RAO is the most common chronic respiratory disease plaguing housed mature horses. It occurs most frequently in the winter when horses are stabled more frequently. Conversely, summer pasture–associated obstructive pulmonary disease, which is clinically in-distinguishable from RAO, is mostly found in southern regions, where horses are kept on pasture throughout the year.

    Who is affected?

    Horses older than 5 or 6 years of age are most frequently affected, and the prevalence increases with age. There does not seem to be a predisposition for gender, but breed and heredity seem to be involved. A study using a control group found an important effect of the sire on the prevalence of RAO in a population of horses. The typical profile of a horse for a diagnosis of heaves is usually a mature horse kept indoors most of the time with limited environmental control of allergens.

     What causes RAO?

    Hay contains microorganisms such as bacteria and fungi as well as tiny particles of feed grains, plants, feces, dander, and pollen. These tiny particles become aerosolized in hay dust and elicit an allergic response when they are inhaled by horses. While it is believed that the hypersensitivity reaction seen in horses is in response to many different allergens, the primary microorganisms involved in the etiology of heaves are Aspergillus fumigatus, Thermoactinomyces vulgaris, and Faenia rectivirgula. Aspergillus fumigatus is a mold that grows on dead and decaying matter such as poorly cured hay. It is thermophilic ("heat-loving") and can thrive in the high temperatures achieved in decomposing vegetation. A. fumigatus forms spores which become airborne and can be inhaled. These spores are antigenic (they are recognized as "foreign" by the immune system and provoke an immune response) and allergenic. Both Thermoactinomyces vulgaris and Faenia rectivirgula are bacteria which produce spores that become airborne and can be inhaled. All three of these species of microorganisms are numerous in moldy hay.

    Challenge studies with A. fumigatus and T. vulgaris have been conducted that show a change in respiratory function, although not as marked as that seen in clinical cases. Airborne endotoxins are also implicated as an inciting factor. The complete etiology of heaves in horses is still not known.


    Pathophysiology of RAO

    When these allergens are inhaled they cause several events to occur in the lungs. Inflammation and thickening of the tissues of the lining of the bronchioles (airways), constriction of the smooth muscles that surround the bronchioles (bronchoconstriction) which also includes coughing, and accumulation of mucus in the airways. These are also the normal natural defense mechanisms used by the lungs to eliminate inhaled particles. The difference in horses with heaves is that the reaction is hyper-reactive in them. 

    It takes only 4 to 6 hours for inflammation to develop in the lungs after allergens are inhaled. When this occurs, neutrophils, specialized white blood cells that kill bacteria, are recruited to the airways in massive numbers. Some of the substances that they release to kill the bacteria can also harm the lining of the airways. Each time a horse with heaves is exposed to allergens this reaction takes place. Over time, the repeated episodes result in edema and thickening of the airways that obstruct normal airflow.


    Clinical Signs of RAO

    Clinical signs of heaves often start out very subtly. It may just be a slight nostril flare or a very slightly faster respiratory rate. These early signs can easily be missed. Most owners first notice a soft cough. This can be during rest or at the start of exercise. It may be accompanied by exercise intolerance. These signs will progressively worsen if the horse is continuously exposed to allergens without treatment. Due to the obstruction of the small airways, a horse with heaves works harder to pull air into and expel air from the lungs than a healthy horse. This increased respiratory work forces the horse to use its abdominal muscles during the late phase of exhalation. Over time, the additional workload results in the visible enlargement of the abdominal muscles and the formation of a heave line. The extra effort of breathing also results in anal pumping, as the horse uses all of its abdominal muscles to expel air. With progression of the disease it becomes increasingly difficult for the affected horse to expel the air from the lungs at the end of exhalation and the lungs may remain over-inflated, which is called emphysema. If left untreated, non-reversible damage to the lung tissue may occur resulting in the permanent loss of lung function.


    Diagnosis of RAO

    Diagnosis of RAO starts with a complete physical examination. Most horses with RAO will have some degree of nostril flare. In later stages anal pumping and a heave line will be noticeable. Most RAO horses will not have a fever, unless they have a secondary bacterial or viral pneumonia. The lungs are ausculted and may reveal an expanded lung field, increased broncho-vesicular sounds (although some low airflow areas may have decreased sounds), expiratory wheezes throughout the auscultation area, and crackles at the periphery of the lung. These abnormalities may be associated with the trapping of air in the lower airway and alveoli secondary to the bronchoconstriction. The higher intrapleural pressure necessary to move the air through the constricted airway increases the velocity of air and the turbulence at the origin of audible noises. When large amounts of tracheal secretions are present, tracheal wheezes may be heard throughout the whole lung auscultation field and even at a distance from the nostrils of the horse.

    Blood work, such as a complete blood count and blood biochemistry analysis, and chest x-rays are often of little value in confirming the diagnosis of heaves. Yet, these tests may be beneficial in ruling out other causes of respiratory disease, such as pneumonia, pleuritis and neoplasms of the chest cavity. Ultrasound can be useful to show pleural roughening and to rule out pneumonia, pleuritis, and neoplasia, as well. Endoscopy can be used to show mucus in the trachea and bronchioles. A transtracheal wash can be performed to evaluated the tracheal secretions for evidence of infection (if pneumonia or secondary pneumonia is suspected) and to look for neutrophils and mucus plugs, called Curschschmann’s spirals, that are indicative of RAO.

    The most reliable way to achieve a diagnosis of RAO is with a bronchoalveolar lavage. Bronchoalveolar lavage is a process whereby a tube is passed through one nostril of the horse into the peripheral airways and then sterile saline is quickly injected and withdrawn from the air passages through the tube. This sample is then analysed microscopically for both the total number of cells present and the number and percentage of each cell type present (i.e. macrophages, lymphocytes, neutrophils, eosinophils, and mast cells). In normal horses, the predominant cells are macrophages and lymphocytes with neutrophils comprising less than five percent of all the cells present. In horses with severe COPD, the percentage of neutrophils in bronchoalveolar lavage (BAL) fluid may be 50-70% (or more) of the total cell count. However, horses with greater than 20% neutrophils will likely have impaired lung function and may have COPD.

    Treatment of RAO

    The best and most effective long term treatment for a horse with RAO is to eliminate exposure to allergens. For many horses, just getting them out of the barn and onto full time turnout will put them into clinical remission. It a horse must be stabled, then it is critical to eliminate as many allergens as possible. This includes eliminating straw and shavings bedding, dry hay, and many grains. Even though the dust levels in the barn may seem insignificant, research has shown that the dust levels in the breathing zone (i.e. around the nose) of a horse eating hay can be as much as thirty to forty times higher than in the rest of the stall. Alternative bedding such as peat moss or newspaper can be used. Haylage or soaked hay can reduce the number of mold spores in the air. Low dust grains are also available. Ideally, horses in adjacent stalls would also be treated the same way to prevent the spread of allergens from their stalls. The overall ventilation of the barn should be evaluated as well. Keep good airflow at all times. Horses don’t need the barn as warm as we would like it in the winter, so don’t be afraid to keep some windows open.

    When management changes are not enough, it may be necessary to administer anti-inflammatory drugs and bronchodilators. Corticosteroids are the drugs of choice for relieving inflammation of the airways. Corticosteroids can be administered by mouth, by injection, or by inhalation. When they are administered by mouth or by injection, therapy usually begins with a high dose and, as the horse improves, the dose is reduced to a maintenance level. Inhaled steroids offer the advantage of a high dose within the airways and minimal systemic side effects but a special mask is necessary for administration.

    Bronchodilators relax airway smooth muscle and relieve airway obstruction. In mildly affected horses, they may be the first line of therapy. They can also be safely combined with anti-inflammatory drugs for treatment of more severely affected horses.  This combination is beneficial because anti-inflammatory drugs can reduce airway wall thickening but have no direct effect on the smooth muscle regulating the diameter of the airways. Bronchodilator drugs can be given orally, by injection, or by inhalation.  Oral administration is the most convenient method but inhalation therapy is the most effective treatment for relief of airway obstruction. As with anti-inflammatory therapy, administration of bronchodilators by inhalation requires the use of a special mask.


    If you suspect that your horse has any signs of RAO, make an appointment with your veterinarian. Early intervention and treatment can help decrease or eliminate clinical signs and allow your horse to return to his normal level of activity. As always, if you horse is competing, be sure to ask your veterinarian about drug withdrawal times.

    Registered 2014 Equestrian Collections; Author:  Sallie S. Hyman,  VMD, DACVIM, CVA  

    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional.  In particular, all horse owners should seek advice  and treatment from a licensed veterinarian for their horses' medical care.         


  • Lyme Disease

     Lyme Disease: Cause, Treatment, Prevention



    Borrelia burgdorferi, the causative agent of Lyme disease, is maintained in a complex life cycle of small wild mammals and immature stages of the black legged tick, Ixodes scapularis (formerly called Ixodes dammini) and Ixodes pacificus. Larval and nymphal stages of the tick acquire the organism when they feed on infected mice. Adult ticks feed and mate on deer during the fall and spring. The female ticks drop off, laying eggs on the ground. After several weeks the eggs hatch into larvae, initiating a two-year life cycle. It is now understood that deer are not a reservoir for Lyme disease, but merely the host for the adult stages of the tick.

    Research has shown that ticks must be attached for at least 24 hours to transmit their disease.  Each stage of the tick, larva, nymph, and adult are capable of transmitting B. burgdorferi. The tick holds the organism in its simplified digestive system, known as a hindgut.  A tick attaches to a host with its very sharp mouthparts.  It then salivates and regurgitates into the host an anti-clotting agent so it can get a ready supply of host blood.  While the tick is attached to the host it uses its mouth parts to suck and ingest blood of the host.  It then sends this blood to its hindgut where it mixes with the organism.  The tick then regurgitates back into the host as it continues to feed.  If the tick had the Borrelia organism in its hindgut, it has now been deposited in the host.  Not only does the host become infected, but is now serves as reservoir of Borrelia for the next tick to ingest when it attaches and continues to spread the disease.

    Lyme disease infects humans and several domestic animals including horses, cattle, dogs, and cats. Like humans, horses are incidental, dead end hosts. Clinical signs are non-specific and include fever, stiffness, muscle pain, and swollen joints. Often the lameness seems to “wander” from limb to limb. Changes in behavior and skin sensitivity (tactile hyper-aesthesia), both with rapid onset, are common clinical signs seen by many practitioners in horses with potential Lyme disease. Borrelia has a strong predilection to infect skin and synovial membranes in the horse, as has been shown in experimental work by researchers at Cornell University. This finding helps support the belief of equine practitioners that stiffness/lameness is a common sign of Lyme disease in the horse. Neurological signs such as depression, dysphagia, head tilt and encephalitis were reported in chronic cases. Most recent reports describe horses with a Borrelia-associated pseudolymphoma or Borrelia-associated uveitis.



    The diagnosis of Lyme disease in animals is currently based on a combination of history, clinical signs, response to antibiotic therapy, risk of probable exposure, and blood tests. It should be emphasized, however, that the results of blood tests do not always correlate with disease status.

    Other causes of vague lameness and performance issues such as equine protozoal myelitis and other causes of neurological disease, osteoarthritis, tendon/ligament injuries and rhabdomyolysis need to be rules out as well.

    Patient-side canine Lyme SNAP tests are being used to identify exposure, but cannot determine is the horse has been exposed in the past, is currently infected, or is positive due to vaccination. Western blot testing has been the gold standard, but results take several days to acquire and the test can be ambiguous.

    The Equine Lyme Multiplex Assay is one of the better means of identifying horses with Lyme disease. This test assays for three outer surface proteins (Osp) of B. burgdorferi. Studies have shown that the Osp antigen expression on the bacterial surface changes in response to tick feeding and again after infecting a warm-blooded host. Horses develop antigens to these Osp proteins in response to infection. Osp A is positive in vaccinated horses. The protein is expressed normally only in the tick, so unvaccinated horses usually have no Osp A antigen. Osp C is the best indicator of early infection. These antigens develop 3 weeks after infection and decline at 7-11 weeks. Osp F is an indicator of chronic infection. Antibodies become detectable at 5-8 weeks post infection and remain high.



    Virtually all cases of equine Lyme disease are treated with doxycycline, tetracycline or ceftiofur. Based upon treatment of Lyme disease in other species, any of these drugs should be effective. Cornell is studying which antibiotic may be most effective.
    Body soreness, muscle soreness, and/or joint pain can be controlled with non steroidal anti-inflammatory agents (NSAIDs).  Inflammed joints are at risk for developing chronic problems or cartilage issues from the inflammatory mediators within the joints.  Therefore, cartilage protective agents (chondroprotection) are often used simultaneously for the best outcome in many cases. 




    Prevention should be aimed at reducing the tick burden on your property. Keep area of pastures where ticks are likely to live mowed and trimmed. Clean up leaves in pastures and yards, ticks like to live here. Protect pets (dogs and cats) from ticks so that they are not transporting ticks into your equine environment.

    Check your horse daily for ticks. Look closely in and around ears, the mane, tail, and neck/chest. Topical fly sprays, spray on or spot on tick preventatives can help to decrease the number to ticks that attach. If your horse does have ticks attached, grasp the tick as close to the mouthparts as possible and pull straight out. Tweezers can be helpful. DO NOT try to burn a tick off with a match.

    There is no vaccine for Lyme disease in horses. Vaccination is currently being done off-label using the canine vaccines. The vaccines have proven to be safe in anecdotal trials, but the effectiveness of the vaccine in horses has not yet been published. Vaccination of at risk populations of horses should be based on a veterinarian’s recommendation.

    Registered 2014 Equestrian Collections; Author:  Sallie S. Hyman,  VMD, DACVIM, CVA  

    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional.  In particular, all horse owners should seek advice  and treatment from a licensed veterinarian for their horses' medical care.      

  • Holiday Hazards

    Holiday Hazards  

    The holiday season is upon us. For many people, this means the fun and creativity of decorating the house for each holiday. And for many, it also means decorating the barn, or at least their own horse’s stall. While getting our equine friends into the holiday spirit may seem like a good idea, it must be done very carefully so that the holiday fun does not turn into a holiday emergency. Many dangers lurk in what may seem like innocent decorations.

    Fall Holidays:

    Fall signals the harvest and Halloween. Pumpkins, mums and dried corn stalks are commonly used to decorate around the barn and arenas, especially at barn entrances and on jump standards.
    Chrysanthemums, sometimes called mums or chrysanths, are flowering plants of the genus Chrysanthemum in the family Asteraceae. Mums are traditional fall flowers and come in a variety of colors. All parts of chrysanthemum plants are potentially toxic to dogs, cats, horses and other mammals. Ingesting the plant can cause vomiting, diarrhea, excessive salivating, rashes or a lack of coordination. How a specific animal reacts to the plant varies, depending on the animal, its size, the amount it consumed and the chrysanthemum species. Horses can experience GI discomfort if they eat a large amount of mums. It is best to avoid letting them munch on the flowers. If they do happen to get into them, monitor their comfort closely and let your veterinarian know in case more severe signs develop.
    Corn stalks make great fall decorations, but care should be used when horses are around. A problem that can occur from a horse trying to eat a corn stalk or the corn cob on it is choke. Often, in their haste to eat something that they know they shouldn’t, horses will inadequately chew the cob or stalk and it will become lodged in the esophagus. Signs of choke include drooling, coughing, feed material coming out of the mouth and nose, and occasionally a “gagging” like response. This is a medical emergency and you should contact your veterinarian immediately to relieve the choke and prevent complications. It is highly unlikely that a horse would become ill from ingesting just a bite or two swiped from a decoration, but all horses should be discouraged from eating corn stalks and any corn that is on them. Corn and the stalks can contain a mold called Fusarium, especially if was grown during a particularly wet season or there was a lot of insect damage. Fusarium produces the mycotoxin fumonisin that causes the deadly neurological disease known as Equine Leukoencehalomalacia, commonly referred to as moldy corn disease. White matter is the brain is affected and produces signs of incoordination, weakness, loss of appetite, and eventually death. Signs can take a week to several months to appear. Once signs appear, there are no treatments that can reverse them. Horses should not be fed corn or corn stalks as a feed supplement unless they have been tested for fumonisins.
    Halloween means treats. We humans love our chocolate and often have bowls of chocolate goodies around the barn. Although a yummy treat, chocolate contains substances that can be toxic to our horses. The toxic substances in chocolate are theobromine and caffeine. Theobromine and caffeine are mild stimulants, bronchodilators, and vasodilators. It is unlikely that a horse would be able to find enough chocolate to consume to induce toxicity, but it is conceivably possible in a mini or small pony. The greater danger is the possibility of having a positive drug screen in a competition horse. Because of the widespread distribution of caffeine, the FEI has removed caffeine from its list of prohibited substances and some regulatory authorities allow a low threshold in plasma and urine samples. However, other jurisdictions have a zero tolerance to caffeine in swab samples. An oral dose of caffeine can be detected for up to ten days. Don’t be tempted to share your Halloween bounty with your horse. It has been shown that the feeding of 10 M&M's® with peanuts would produce a detectable concentration of theobromine and caffeine in the horse's urine for 48 hours.
    Pumpkins are abundant this time of year and can make a good treat for your horse. They can be fed cooked or raw. Just make sure that the pumpkin is cut into manageable sized pieces to prevent choke. Avoid feeding whole pumpkins of any size. A greedy horse may try to swallow a small one whole.

    Winter Holidays:

    Traditional Christmas decorations include many hazards. A little knowledge, planning and common sense can keep your horse safe.
    Pointsettia are one of the hallmarks of the winter holiday season. They come in many beautiful colors and add a festive look. Well, rest assured, poinsettia are safe! This plant has developed an undue bad reputation for being toxic. The milky white sap found in poinsettias contains chemicals called diterpenoid euphorbol esters and saponin-like detergents. Mild signs of vomiting, drooling, or rarely, diarrhea may be seen. If the milky sap is exposed to skin, dermal irritation (including redness, swelling, and itchiness) may develop. Rarely, eye exposure can result in a mild conjunctivitis (“pink eye” secondary to inflammation). Signs are self-limiting and generally don’t require medical treatment unless severe.
    Other holiday plants, however, can be quite toxic. Mistletoe and holly can be toxic to horses. The berries are most toxic, but all parts or the plant contain toxins. In addition, the pointed leaves can cause injury. The plants contain several toxins that cause symptoms of colic, difficulty breathing, slow heart rate and collapse, erratic behavior, tremors and seizures. It is best to avoid hanging holly or mistletoe where your horse might be able to reach it.
    Some smaller ornamental Christmas trees may be of the genus Taxus, commonly referred to as Yew. This evergreen shrub has fleshy red seed coverings. All parts of the yew plant, both fresh and dried, are extremely toxic to horses. The plant contains taxine, a toxin that affects cardiac activity. Consumption of as little as 1-10 g/kg of body weight for ruminants and 0.5-2 g/kg for horses is lethal. This means that, for a 454-kg (1,000-lb) horse, as little as 227 g (0.5 lb) of yew needles could be fatal. Sudden death, often within 2-3 hours of ingestion, is the most common observation with yew poisoning. Animals are often found dead next to yew bushes or clippings. Prior to death, muscle trembling, incoordination, nervousness, difficulty breathing, slow heart rate, vomiting, diarrhea and convulsions may be observed. There is no antidote for yew poisoning, only supportive treatment.
    Christmas decorations such as ornaments, tinsel/garland, and lights should also be placed with care. Curious horses will try to eat ornaments that might look like yummy fruit to them. These can result in choke or an intestinal foreign body that can result in colic. The same goes for stockings with carrots or other horse treats. Your horse may decide it is easier to eat the whole stocking than to pull out the treats.
    Christmas lights should be carefully inspected to ensure that they are not a fire hazard and should be placed so that horses cannot pull on them or the extension cords. Both lights and garland should be carefully secured so that horses cannot get tangled up in them.
    The holidays should be a time of fun and festivities. With a little knowledge and common sense, you can make the holidays happy for you and your horse.  Stick to safe Horse Treats this holiday season!
    Registered 2014 Equestrian Collections; Author:  Sallie S. Hyman,  VMD, DACVIM, CVA
    Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional.  In particular, all horse owners should seek advice  and treatment from a licensed veterinarian for their horses' medical care.       


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