• What is Equine Metabolic Syndrome?

Equine metabolic syndrome is a recently recognized medical problem in horses. Basically some horses that are constantly provided an excess of soluble carbohydrates over their needs develop a situation where their cells become resistant to the influence of insulin to move glucose into cells for energy use. Because they constantly have more glucose in their bloodstream they continue to produce more and more insulin. Recent research has shown that high levels of insulin can and does cause laminitis in horses. We think that some horses have a genetic predisposition to this problem and are the ones we often refer to as easy keepers. Overweight horses produce more cortisol which also influences insulin.

• How do I know if my horse has Equine Metabolic Syndrome (EMS)?

Most horses with Equine Metabolic Syndrome or EMS have a typical physical appearance or phenotype. They will usually have a very cresty neck and fat pads over the lower back and around the tail head. They put on weight easily on normal amounts of feed. Laboratory testing can confirm the diagnosis of EMS through evaluation of fasting insulin levels.

• What is the difference between Equine Metabolic Syndrome and Equine Cushing’s Disorder?

Equine Metabolic Syndrome seems to be a genetic linked syndrome in horses that descend from lines that developed in regions of the world where feed sources became scarce during certain times of the year. These horses developed the ability to store fat readily for reserves during times of reduced feed supply. In comparison, horses with Equine Cushing’s Disorder (ECD) develop an abnormal production of hormones from the pituitary gland (the major hormone control center) that manifests in a number of different clinical signs. These horses are usually older and may have a long curly hair coat that does not shed out well in the summer; they may have a loss of muscle tone, are usually less resistant to infection and often develop laminitis. ECD is generally diagnosed through analysis of the ACTH levels in the horse’s bloodstream along with a low dose dexamethasone suppression test of the cortisol levels. Cushing’s Disorder can be managed with medication, most often a drug called pergolide.

• What are the dangers of EMS to my horse?

Horses with EMS are usually obese and can have all of the health problems associated with obesity in any animal such as an increase in joint problems and exercise intolerance. The most devastating problem associated with EMS is laminitis. Horses with elevated insulin levels are very susceptible to this crippling disease. Laminitis is currently the second leading cause of death in horses. Equine Metabolic Syndrome is one of the leading causes of laminitis.

• Managing the horse with Equine Metabolic Syndrome

Diet and exercise are the most important aspects of managing EMS. A diet low in non-structured carbohydrates (NSC) is very important. No grain, limited or no pasture, hay that is low in NSC, no additional sources of sugars (like molasses) are extremely important. Hays that are grown under adverse conditions may be higher in NSC’s than other hay. Legumes (clover and alfalfa) are generally higher in NSC’s than grass hays. Research has shown that insulin levels can be kept down with 30 -45 minutes of exercise daily. The effect from exercise does not last more than a few days, so the effort to exercise the horse must be maintained even when you are unable to personally see to it. When you are on vacation, arrange for someone to exercise your horse for you. It is helpful to monitor your horse’s weight, girth size and the circumference of his neck to keep track of how you’re doing managing his EMS. It is also valuable to periodically have your veterinarian check the fasting insulin level in the horse’s bloodstream. The insulin level can be an important predictor of laminitis. If your horse has an elevated insulin level it is wise to have radiographs taken of the horse’s feet to look for evidence of laminitis. Many horses will have had bouts of laminar inflammation that were sub clinical or that were misinterpreted as just sore feet. Measurements of the position of the coffin bone within the hoof capsule will determine the status of the horse’s hoof health and provide a good baseline should the horse develop painful signs of laminitis. These radiographs also serve as a blueprint for the farrier to provide proper mechanical advantage to protect laminar structures of the foot. Occasionally your veterinarian may prescribe thyroid supplementation for a period of time to help with weight loss. Again diet and exercise are the key points to managing the horse with Equine Metabolic Syndrome.