Vets have a few PPID testing options, the most common of which is measuring horses' blood ACTH levels, which tend to be elevated in affected horses. | Photo: Alexandra Beckstett/The Horse

It wasn’t long ago that veterinarians diagnosed pituitary pars intermedia dysfunction (PPID, previously known as equine Cushing’s disease) based solely on clinical signs. But as their understanding of the disease progressed, so did the diagnostic protocols and tests.

Today, vets have a few PPID testing options, the most common of which is measuring horses’ levels of adrenocorticotropin hormone (ACTH), which tend to be elevated in affected horses.

This hormone, however, is fragile in whole blood samples, meaning its levels can fluctuate if not handled carefully, said John Haffner, DVM, an associate professor at Middle Tennessee State University, in Murfreesboro