Equine Metabolic Syndrome

Equine metabolic syndrome (EMS) is a disease of a horse's endocrine system. Endocrine disorders are responsible for imbalances, and EMS is one of the more commonly diagnosed defects of this complex system. University of Illinois researchers call EMS a "prosperity disease" because it affects horses that are fed a rich diet, particularly certain breeds that are considered "thrifty." A thrifty horse is one that is able to survive on little feed and in harsh conditions. Living under the more indulgent conditions of typical domestic horses, thrifty horses can quickly become overweight, insulin-resistant and prone to laminitis.

  1. EMS Symptoms

    • Equine metabolic syndrome usually affects horses between the ages of 6 to 20 years. According to Henry Greenwald of Equine Medicine and Surgery in Seattle, Washington, EMS is "most commonly seen in ponies, domesticated Spanish Mustangs, Paso Finos, European Warmbloods, American Saddlebreds, Arabs and Morgans." Signs may include obesity, insulin resistance and recurrent founder or laminitis. Unevenly distributed fat deposits may accumulate of the neck, tail and shoulders, but some horses show no symptoms, particularly if they are exercised frequently.

    Diagnosing EMS

    • Symptoms of EMS are similar to equine Cushing's disease, so blood tests are needed to differentiate between the two conditions. Unlike horses suffering from Cushing's, horses with probable EMS will show high insulin levels and normal cortisol levels.

    EMS Dangers

    • EMS causes founder or laminitis in horses. Recurrent attacks can damage the hoof laminae and cripple the horse. Because some EMS horses that get regular exercise do not gain weight, laminitis may be the only symptom. Keep an eye out for any signs of lameness, an early symptom of laminitis.

    Treatment

    • Currently, there is no cure for EMS. Some medical options are available, but they are expensive and, according to the University of Illinois Extension, best used as a temporary measure. A better option is dietary management. Horses should be fed grass hay that has a low glycemic index. Have your hay tested by a reputable testing agency to determine the sugar and starch content of your hay.

    Prevention

    • Restrict pasture access, particularly during the early spring. Your local cooperative extension can help you manage your pastures to create a better environment for an EMS-afflicted horse.

      If your horse has been diagnosed with EMS, do not feed grain or treats like carrots, apples, pears, molasses or wheat bran.

      There are specialty pelleted feeds for horses with insulin resistance, and these may be a good choice for your horse--but check with your vet before switching feeds.

      Exercise is helpful, but if your horse is suffering from laminitis, the hoof must be stabilized before undertaking any activity.