Equine Metabolic Syndrome

Equine Metabolic Syndrome (EMS) is a hormonal condition mostly associated with insulin resistance. EMS usually develops in equines between five and 16 years old and affects ponies more than any other types. EMS can be a problem because it usually triggers laminitis, an inflammation of the laminae inside the foot. Laminitis can be extremely painful and have lasting repercussions for the equine.

EMS Fact Sheet

Causes of Equine Metabolic Syndrome

Insulin is a hormone produced by the pancreas which regulates glucose (simple sugar) in the blood. When it’s released, insulin attaches to the glucose so it can be absorbed into the muscle and liver cells.

Resistance means the cells in the muscles and liver don’t respond well to insulin. Therefore, the cells can’t use the glucose in the blood for energy.

This makes the pancreas create more insulin and over time the blood sugar levels go up. As the glucose isn’t being used, the molecules bind together to make triglycerides and are stored as fat around the body. These fat pads are usually found along the neck, withers, loins, tailhead, ribs and behind the shoulders.

Hyperinsulinemia, elevated levels of insulin in blood, creates a vicious cycle where the body releases more and more insulin. This action inhibits lipolysis which is the process of breaking down fat stores from the body for energy.

Other factors which influence insulin are thyroxine and adiponectin. Thyroxine is a thyroid hormone which affects metabolism. Adiponectin is a protein hormone which increases insulin sensitivity and regulates glucose levels. Obesity suppresses its secretion.

In some cases, the equine can still be thin but they will have a high amount of internal fat around the organs.


• Sudden bouts of laminitis
• Obesity, a body condition score above 4
• Abnormal fat pads around the body (excess
adipose tissue)
• Thick, hard crest along the top of the neck
• Difficulty losing weight
• Dull demeanor
• Increased drinking
• Increased urination


Testing is necessary to find out if your equine has EMS. Early treatment can prevent the negative consequences of EMS. If you notice any signs, contact your vet and a karo test will be administered.

The test will measure the equine’s insulin response after eating karo light corn syrup (a sugar syrup).

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