Equine Metabolic Syndrome

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Equine Metabolic Syndrome:  Equine Metabolic Syndrome, or “EMS”, is a term used to describe horses with insulin dysregulation who are at increased risk for laminitis. When a healthy horse eats, their body releases a specific amount of insulin into the bloodstream in a balance with how many carbohydrates they have eaten.  In horses with EMS, the body releases excessive amounts of insulin in response to carbohydrates.  Over time, these high levels of insulin can lead to laminitis, or “founder”.     Horses with EMS are often described as “easy keepers” because they tend to gain weight easily.  Horses with EMS typically have fat deposits such as cresty necks, fat pads behind the shoulders, and fat pads at the tail head.  Lean horses can also have EMS, however, it is less common.  Signs that a horse may be affected by EMS include obesity, fat deposits, and forelimb lameness caused by laminitis. 

If we suspect that a horse has EMS, we can run a blood test to check their insulin level.  About ⅓ of horses with EMS also have Equine Cushing’s Disease, so we will often test for Cushing’s at the same time we check insulin levels.

It is very important to manage horses with EMS because they are at increased risk for developing laminitis if their insulin levels stay elevated for prolonged periods.  Laminitis is a painful condition that can have a significant impact on quality of life. If your horse has EMS, it is important to make a dietary plan with your veterinarian.  As a general rule, horses with EMS should be fed hay in amounts equivalent to about 1.5% of their body weight daily.  For example, a typical 1000 lb horse would eat 15 lbs of grass hay per day.  The non-structural carbohydrates (NSC) content in the hay should be <10%.  If it is not possible to test your hay to find out the NSC content, the hay should be soaked in cold water for 1 hour to reduce the amount of carbohydrates it contains.  Unfortunately, grass pasture is often high in NSCs, so it is not recommended for horses with EMS to be turned out on grass.     Most horses with EMS do not need grain to maintain healthy body weight.  Horses who are “easy keepers” can be fed a small amount of ration balancer to ensure they get enough protein, vitamins, and minerals in their diet.  A few examples of ration balancers are Nutrena Empower Topline Balance or Purina Enrich.  For horses with EMS who need grain to stay at a healthy weight, it is crucial to find a truly low carbohydrate grain.  Many grains claim to be “controlled sugar” but are still above the recommended percentages for EMS horses.  When looking for a low carbohydrate grain, it is important to check the NSC %.  The total NSC should be as close to 10% as possible.  If NSC is not listed, you can calculate NSC by adding starch + sugars.  For example, a grain that has 10% sugars and 10% starches would have a total NSC of 20%. Exercise is important for managing horses with EMS.  Exercise can help with weight loss and improve insulin levels.  Horses who are sound (not horses who are suffering from active laminitis or are otherwise lame) should be put into a consistent exercise regimen. For many horses, exercise, weight loss, and dietary changes are enough to bring their insulin levels back down into the normal range.  For horses who still have high insulin despite these changes, there are also medications your veterinarian can recommend to help reduce insulin levels further. 

If you suspect your horse may have Equine Metabolic Syndrome, please call us to discuss your concerns with one of our veterinarians.