Veterinarians can typically diagnose a horse with late-stage pituitary pars intermedia dysfunction (PPID, or equine Cushing’s disease) easily. Diagnosing early stage PPID and, thus, allowing treatment to begin earlier in the course of the disease, remains more challenging. Fortunately, research is ongoing and more reliable diagnostic tests are being developed.

At the 2013 Western Veterinary Conference, held Feb. 17-21 in Las Vegas, Nev., Hal Schott II, DVM, PhD, Dipl. ACVIM, professor of equine medicine at Michigan State University’s College of Veterinary Medicine, described the current diagnostic options for PPID.

PPID Basics

Schott first reviewed PPID, a disease caused by an enlargement of the pars intermedia of the pituitary gland (the central part of the pituitary gland located at the base of the brain) that affects all breeds and types of horses. Many affected horses are older than 20; however, the disease has been recognized in some younger horses, as well. There’s no gender predilection.

Schott described some common clinical signs of horses with advanced PPID:

  • They have a characteristic long hair coat that fails to shed properly (a condition formerly known as hirsutism in these horses, but recently studied and renamed hypertrichosis, which means hair growth that is abnormal in quantity or location, Schott said);
  • Affected horses often have abnormal sweating patterns;
  • They experience polyuria and polydypsia (excessive urination and drinking, respectively); and
  • About 60% of affected horses experience muscle wasting with or without associated weight lo