PPID (Cushing’s)

Pituitary Pars Intermedia Dysfunction (PPID, also known as “Cushing’s”), is when the pituitary gland, which is responsible for producing hormones, is not functioning as it should. This causes excessive production of specific hormones. The gland is located at the base of the horse’s brain, and it is thought that degenerative stress is a major key cause. PPID occurs when the pituitary gland grows excessively, sometimes caused by a mutation, and other times caused by benign (harmless) tumours increasing its size. The gland secretes a hormone called ACTH (adrenocorticotropic hormone), which regulates, amongst other things, cortisol levels.

As PPID causes increased ACTH secretion, this, in turn, increases cortisol production, which is known as the “stress hormone”. This can increase sugars (glucose) in the bloodstream. Horses diagnosed with PPID often need a strict low sugar and starch diet. Although there is no cure for PPID, it can be managed with medication. If your horse shows symptoms of PPID, contact your veterinary surgeon for advice.

Initial Symptoms

  • Increased coat length and late shedding of the winter coat
  • Increased sweating (hyperhidrosis)
  • Lack of energy for no apparent reason (lethargy)
  • Unexpected weight loss (anorexia)
  • Excessive drinking and urinating (polyuria and polydipsia)
  • Potential laminitis flareups

Top Tips

  • Consult vets for possible treatments including dopamine agonists, serotonin antagonists and cortisol antagonists.
  • A low-carb, high-fat diet can help counter the effects of muscle loss without risking insulin resistance (a related illness that can occur in some horses with PPID).
  • Limit access to rich forage such as spring grass and haylage.
  • Consider clipping in the summer to keep the horse call in warm weather.