The facts on EMS

Previously called “peripheral Cushing’s syndrome,” “hypothyroidism” and even “Syndrome X,” equine metabolic syndrome (EMS) is now much better understood thanks to concentrated research efforts.

Rather than describing one specific condition, the term EMS encompasses a collection of signs and clinical changes, including insulin resistance, hyperinsulinaemia, infertility and obesity. Fat deposits are one of most distinct physical signs of EMS; horses with the condition tend to accumulate fat along the top of the neck, over the ribs and the top of the tailhead, giving the horse a very “rounded” appearance.

EMS is often evident in horses between the ages of 5 and 16, and it is seen more frequently in ponies and some breeds, including Morgans, Paso Finos, Tennessee Walking Horses and mustangs. These horses are thought to have a “thrifty” gene that allows them to survive in harsh environments. However, in a domestic setting where there is plentiful food, this increased metabolic efficiency leads to insulin dysregulation and obesity.

Horses with EMS are also more likely to develop pituitary pars intermedia dysfunction (PPID; also called equine Cushing’s disease). In addition, EMS horses are most certainly at increased risk of developing laminitis.

TELLTALE: One characteristic of equine metabolic syndrome is the accumulation of fat on top of the neck, over the ribs and at the top of the tailhead.