Similar but Different: Equine Cushing’s Disease and EMS

Equine Cushing’s Disease and Equine Metabolic Syndrome (EMS) are common endocrine disorders in horses that share some of the same clinical signs, so how do we separate the two conditions?

"It is important to examine the history, animal, and laboratory results when considering endocrine disorders in horses," says Nicholas Frank, DVM, PhD, Dipl. ACVIM, professor of Large Animal Medicine at Tufts University. "Equine metabolic syndrome is likely to have a genetic basis and horses are often obese and have a history of gaining weight on limited calories. They are usually younger when EMS first develops and this condition predisposes them to laminitis. In contrast, horses with Cushing’s disease, which is better referred to as pituitary pars intermedia dysfunction (PPID) are middle-aged or aged when clinical signs appear and often have a leaner body condition. "

Management of EMS primarily focuses upon weight control and dietary changes, Frank said. In contrast, the drug pergolide is prescribed to manage Cushing’s disease by suppressing the activity of the pars intermedia.

This article aims to make sense of the world of Cushing’s and EMS. We’ll describe the diseases’ primary features, compare clinical signs and available diagnostics, and highlight key treatment differences