Brief Description

Equine Metabolic Syndrome (EMS) is a problem that is most frequently diagnosed initially in horses <15 years old. It is often associated with laminitis, obesity and a combination of endocrine disorders. Those endocrine disorders include insulin resistance, hypothyroidism and Equine Cushing’s. Genetics and the environment also play a significant role in Equine Metabolic Syndrome as well.


Diagnosing Equine Metabolic Syndrome

The first thing we as veterinarians will do is a physical exam. There are many clinical signs of EMS that can be assessed this way. Horses with EMS often have regional adiposity (fat deposits in specific areas). These areas include the crest of the neck, behind the shoulders, and around the tail and head. We may also check with hoof testers for foot soreness and other signs that may indicate your horse has laminitis. Your veterinarian may also offer blood work to test for EMS.

Pictured: Horse with regional adiposity.


Diseases Commonly Associated with EMS


Insulin Resistance: This is a common component of EMS in horses. When horses are insulin resistant, it means they do not metabolize glucose correctly and are at an increased risk of laminitis.


Laminitis: Laminitis is a disease that affects the feet. Laminitis simply means inflammation of the lamina which are the tissues responsible for holding the horse’s hooves together with their coffin bone. You may not know this, but horses stand on the equivalent of your middle finger nail! That’s a lot of weight to carry, so when there is inflammation in the laminae the coffin bone can rotate or “sink” which causes a lot of pressure and pain.





Equine Cushing’s (Pars Pituitary Intermedia Dysfunction): Equine Cushing’s is a clinical syndrome that results from a tumor on the horses Pituitary. This is not the same disease process as Equine Metabolic Syndrome but can occur simultaneously. Common clinical signs of Equine Cushing’s are recurring hoof abscesses and long haircoat (called hirsutism) or delayed shedding out as compared to previous years. This disease is typically first noticed in horses that are >15 years old.

Example of a horse with Cushing’s that has hirsutism.


Hypothyroidism: Low circulating thyroid hormone often contributes to a metabolic horses’ inability to lose weight efficiently. Testing thyroid levels and supplementing as needed can help your horse lose weight appropriately and avoid the other sequelae of EMS (such as laminitis).


Management of EMS

Management of EMS largely centers around dietary changes. Much like a human diabetic, managing circulating blood glucose and optimizing insulin regulation by limiting carbohydrates is crucial. Here are a few management changes you can make at home:

  • Feed moderate quality grass hay that has been soaked in water for 30 minutes prior to feeding (DO NOT GIVE THIS WATER TO THE HORSE). This reduces the sugar content of the hay. There are laboratories that will test your hay for sugar content etc. which can help you make the best choice for your metabolic horse.
  • Use a grazing muzzle when your horse is on pasture (especially in spring when grass is young and lush).
  • IF your horse is not laminitic, then increasing exercise is very important to help your horse lose weight at an appropriate rate. Losing weight too fast can be dangerous to overall health and organ function.