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  • Equine Metabolic Syndrome (EMS)

Is your horse or pony overweight or obese?

Maybe you have already tried to reduce their food but you still have not noticed any improvement in their weight?

Can you see fat accumulation? In particular on the neck, shoulders or tail head region?

Maybe laminitis is also a problem?

Equine Metabolic Syndrome (EMS) might be the answer to your problems.

What is EMS?

EMS refers to horses/ponies/donkeys that are not able to metabolise carbohydrates from their diet correctly. This abnormality has been termed insulin dysregulation. This means that the blood glucose level doesn’t go back to the normal range after eating as it would do in healthy horses. Insulin plays a key role in the control of glucose levels in the blood. If the horse acquires a resistance to insulin it means that the horse cannot keep blood glucose levels at a normal level. This can lead to changes in the metabolism, in the fat composition, clotting disorders, inflammation and damage to blood vessels. This potentially can lead to alteration in the blood vessels in the feet and laminitis.

EMS can affect horses and ponies of any age (higher risk in young and middle age animals) and breed, but it has been recognised that the risk is higher in some breeds including Welsh, Dartmoor, Shetland Ponies and Morgan, Arabian and Warmblood horses.

Clinical signs include (one or more of the following):

  • Overweight/Obesity (see Body Condition Score-BCS information sheet)
  • Fat accumulation on neck, shoulders or head tail regions
  • Laminitis
  • Lethargy
  • Increased urinary production and water intake (Polyuria/Polydipsia)


It can be diagnosed with a simple blood test to check the insulin and glucose concentration and insulin response.

The tests include:

  • Single blood sample
  • Oral Glucose Challenge Test. Speak to one of our vets for more information as this blood test has to be arranged in advanced (the horse needs a 6 hours starvation period followed by administration of oral glucose 2 hours prior to the blood sample).


This syndrome can be treated but it requires dedication!

Increased exercise and a low energy diet is required, fat and highly soluble carbohydrate should be avoided. The aim is to control the body weight so that the insulin receptor can become sensitive to insulin again.

Access to pasture should also be managed carefully.

In some cases medication (Metformin) can be given, but weight control remains the major key on the control of EMS.