Equine metabolic syndrome in horses

What is equine metabolic syndrome (EMS)?

Equine metabolic syndrome (EMS) is a disorder associated with inappropriate blood insulin levels (insulin dysregulation) along with a combination of increased fat deposition and a reduced ability to lose weight. Although not a disease in its own right, EMS can increase a horse’s risk of developing laminitis through insulin dysregulation and obesity or abnormal fat deposition.

“Laminitis is a hallmark of EMS and when they succumb, the insulin in their bodies is very high because they are not able to regulate their insulin properly,” explains Rowan Wright, Director and Veterinary Surgeon of Thornton Wright Equine. “This high level of insulin then drives laminitis which is essentially inflammation of the laminae, the soft-tissue structure in the foot between the outside hoof wall and the bone. They can also develop abnormal fat deposits and be sluggish and lethargic. It’s quite often missed in competition horses because they are not the typical stereotype.”

What type of horses can have EMS?

Any age and type of horse or pony can have EMS, but British native ponies, Shetlands, minis and donkeys appear to have a higher incidence. A lack of exercise and veteran horses are also more likely to develop abnormal blood insulin levels.

Often, horses with EMS are very overweight and have abnormal fat deposition such as on the crest of the neck, over the shoulders, over the back musculature and in the rump area. However, lean horses can also suffer from EMS, which is why it is important to confirm abnormal blood insulin levels through relevant blood tests.

How is EMS diagnosed?

EMS is diagnosed based on the horse’s history, appearance and clinical examination findings. However, blood work is required to confirm abnormal blood insulin levels. Your vet will discuss the tests available that will be suit your horse with you.

How can EMS be treated?

Managing EMS is usually done through correct diet and exercise, but patience and dedication is required.

• Feeding a horse with EMS
  Ask a nutritionist to assess your horse’s diet and suggest an appropriate feed regime. Grazing should be restricted or even stopped altogether until the horse’s blood insulin levels have returned to normal and the patient has lost a suitable amount of weight.
  Hay should be trickle fed via double-netted haynets or hay balls, at a rate of 1.5% of body weight in kg of hay per day and preferably soaked for 8-12 hours. A low-calorie balancer or vitamin and mineral supplement should also be fed and can be fed alongside light, unmolassed chaff or unmolassed sugar beet pulp.

• Exercise is vital
  Exercise improves cellular insulin sensitivity, so introducing and building exercise in an EMS horse is a great way to not only encourage them to lose weight, but also keep his insulin levels healthy. However, if your horse or pony is laminitic, wait until they have been given the all clear by your vet before starting a gradual exercise programme.
  In horses not actively laminitic, a good rule of thumb is to aim for at least twenty minutes of continual trot or canter work at least five times per week.
  Once weight loss has been achieved, blood work can be repeated to assess the horse’s response to the management changes.

• Medication options
  There are a number of drug therapeutic options to help in severe and non-responding cases and can be particularly useful in cases of laminitis where exercise is not permitted. Speak to your vet about the options.

Approved by horse veterinarian Annette Graf, March 2024.