EMS: Equine Metabolic Syndrome

Written by University of Florida veterinary student Josie Irvine

Equine Metabolic Syndrome (EMS) is an endocrine disorder commonly seen in overweight horses, ponies, and donkeys. Animals affected by this disorder have issues related to the release and function of insulin, which is known as insulin dysregulation. Animals with insulin dysregulation have systemic inflammation and hormonal imbalances which puts them at high risk for laminitis. This makes diagnosis and control of this disorder extremely important as laminitis can be a terminal condition.

Animals presenting with this condition are typically overweight and have a history of being “easy keepers”. Excess fat distribution can be seen on the crest of the neck, above the tailhead, and in the prepuce or mammary gland. Owners may also complain about their horse not losing weight despite intense caloric restriction.

If you are concerned that your horse may have equine metabolic syndrome, diagnosis of the disease can be done with a blood test to measure blood insulin levels. This method of diagnosis is adequate for diagnosing moderate to severe EMS, but some animals may require an oral glucose test.

Treatment of the disease focuses on promoting weight loss through dietary management and increasing exercise. It is important to feed a diet that is low in simple carbohydrates and restricting pasture grazing. A diet plan that ensures safe and effective weight loss should be discussed with your veterinarian. Additional medications may be prescribed to aid in weight loss, increase the body’s sensitivity to insulin, or decrease the blood glucose. Proper treatment will reduce clinical signs and decrease the risk of laminitis, but there is no cure for EMS and owners must be aware that the treatment will be lifelong.

While there is a genetic component to Equine Metabolic Syndrome, efforts can be taken to prevent the disease from occurring. Prevention focuses on maintaining healthy weights in horses, particularly “thrifty” breeds that are at higher risks for EMS. If you have any further questions regarding EMS or weight management in your horses, please contact your veterinarian.