April 2014

Corticosteroid Use in Horses

Corticosteroids are a group of drugs used in the treatment of a variety of ailments in horses (and other species of animals for that matter). They are often called steroids for short, which is confusing because these are not the same as anabolic steroids used to enhance muscle development and promote weight gain. In fact, the functions of corticosteroids are quite different from anabolic steroids.

Corticosteroids are synthetic versions of a natural hormone the body produces called cortisol. This hormone is responsible for many functions such as water and electrolyte balance, stress regulation and has strong anti-inflammatory properties. Corticosteroids are used for many types of cases such as allergic, neurological, dermatological, and respiratory conditions. They are sometimes used in cases of shock and very frequently used for their anti- inflammatory effects in joints affected by arthritis.

There are many corticosteroids used in veterinary medicine. You are probably familiar with some of them. Dexamethasone, prednisolone, isoflupredone (Predef), triamcinolone (Kenalog), and methylprednisolone (Depo- medrol) are just few of the steroids used for horses. Corticosteroids come in a variety of formulations depending on the drug, including solutions for intra-articular (for in joints), intravenous, or intramuscular use, and pills, powder or liquid for oral administration. Topical products are also available.

With the benefits of corticosteroids there are also some risks associated with their use. Although uncommon, the main concerns with steroids are the following:

1) Immune suppression- because of how this class of drugs works, horses often experience immune suppression, primarily when higher doses are used. This can increase the horse's susceptibility to bacterial, viral and fungal diseases.

2) Laminitis-this is more likely to occur in horses or ponies that are overweight, have equine Cushing's Disease, or have had laminitis previously.

3) Gastric ulcers- high doses of corticosteroids alone or using them in combination with non- steroidal anti-inflammatories (NSAIDs) such a bute or banamine increase the risk of developing stomach ulcers.

Given the risks described above, veterinarians are very careful when selecting which cases these medications are best used for. Sometimes when they are used, other medications such as antibiotics and ulcer preventative medications are given as adjunctive therapies. Corticosteroids are administered at the lowest effective dose to reduce the risks while still providing benefits. Horses that are on steroids for an extended period (such as those being treated with prednisolone for heaves) need to be weaned off of the drug so that their body can begin to make its own cortisol. With short term use (a few days) the drug can usually be stopped abruptly.

Corticosteroids have withdrawal times for competition, meaning they cannot be given a specified amount of time before a race or horse show. These times vary by drug and competition type, so be sure to check with your veterinarian before administering these medications.

---

The Value of Post-Mortem Examinations

It is quite shocking when you walk out to a pen and find an animal that was showing no signs of problems a few hours previously, dead. As we all know these things sometimes happen...however, it often makes financial sense to identify the cause of death in order to prevent the same thing from happening to other animals in your herd.

When faced with abortions, stillbirths, disease outbreaks and sudden death cases, we can come to your farm and perform a post-mortem exam. In doing so, we examine the animals' environment, we collect a thorough history on the animal (vaccination status, previous treatments, pregnancy status, etc...), perform an exam of the exterior of the animal, followed by a thorough exam involving cutting open the animal. Generally we collect samples and send them to a laboratory for them to help identify a definitive or probable cause. For abortion and stillbirth cases we also need to examine and submit samples of the placenta as well. Using the post-mortem exam and lab results, we can come up with vaccination protocols or other treatment recommendations to help prevent further disease or death within your herd.

For best results, post- mortems need to be done as close to time of death as possible to prevent deterioration of tissues and overgrowth of bacteria. It is also preferable that the animal stay out of the sun and not be frozen prior to sample collection. The cost of an on-farm post-mortem exam including submission of samples to the lab generally costs less than $375...a lot less expensive than losing many animals to a respiratory or diarrhea outbreak for example.