The two major endocrine disorders affecting horses–equine metabolic syndrome (EMS) and pituitary pars intermedia dysfunction (PPID or equine Cushing's disease)–were hot topics at the 2009 American Association of Equine Practitioners (AAEP) Convention in Las Vegas, Nev., Table Topic session on Equine Endocrine Disorders.

The more recently described EMS is a condition that first develops in younger (less than15 years of age) horses and is likely to have a genetic basis. Affected animals show enhanced metabolic efficiency and might be described as "easy keepers." They readily become obese when overfed and develop enlarged fat deposits in the neck and tailhead regions.

Horses and ponies with EMS suffer from insulin resistance, which is an endocrine disorder associated with increased laminitis susceptibility. Obesity and insulin resistance should therefore be managed to lower the risk of laminitis.

In contrast, PPID, which is also called equine Cushing's disease, is an endocrine disorder that usually develops in older (greater than 15 years of age) horses. Classic signs of advanced PPID include a long, curly haircoat (hirsutism), delayed shedding of the winter haircoat, loss of muscle mass, increased drinking and urination, pot-bellied appearance, and increased susceptibility to infections