Pituitary Pars Intermedia Dysfunction (PPID) or Equine Cushing's Disease

PPID = Pituitary Pars Intermedia Dysfunction
It can also be called “Equine Cushing’s Disease”

To break that down, let’s focus on the first three words – Pituitary Pars Intermedia

The pituitary is a small gland within the brain and the pars intermedia is a cluster of cells within the pituitary. Nerves (from the nearby hypothalamus) release dopamine onto these cells. Dopamine limits these cells activities, keeping hormones in balance.

Some horses will have a degeneration of these nerves leading to a dysfunction of these cells. With less regulation, these cells release excess products, such as ACTH, into the bloodstream.

This imbalance in hormones, leads to the clinical signs of PPID:
- hypertrichosis (excessive hair)
- patchy hair shedding
- muscle loss (usually along the horse’s topline)
- chronic infections
- laminitis (specific type of foot soreness that can lead to founder)

If your horse is suspected of having PPID, your veterinarian may recommend measuring its ACTH or other hormones. Always consult with your horse’s veterinarian for specific testing and treatment recommendations.

References:
Smith’s Large Animal Internal Medicine Sixth Edition textbook