Symptoms of EMS

Overweight or fatty deposits can be a sign of EMS

Large horses in field
Horses can put on weight with EMS


EMS shares some attributes with Type II diabetes in humans, and is characterised in horses and ponies by:

  • Being overweight and/or having abnormal fat distribution (therefore this disorder can occur in normal or even underweight animals that have abnormal fat deposits).
  • Insulin resistance and having high circulating blood insulin levels (a hormone that helps to regulate blood sugar).
  • Laminitis, which can range from recurrent mild episodes to severe laminitis that persists or recurs despite good management and veterinary treatment.

Certain breeds are particularly susceptible to EMS, especially native British pony breeds, but the condition is also seen in many horse breeds. We see more cases of laminitis in horses and ponies with EMS in the spring because when they ingest higher level of sugars in the grass, it results in higher levels of circulating glucose and insulin. This increase can exacerbate their existing insulin resistance and therefore increases their risk of laminitis. But remember grazing on its own is unlikely to cause laminitis if there is not an underlying endocrine problem.

It’s important to note that many horses and ponies have both PPID and EMS, and therefore should be screened for the presence of both disease.