Riverina Equine Vet



Cushing's Disease (PPID)

What is PPID?


Pituitary Pars Intermedia Dysfunction (PPID), also known as equine Cushing’s disease, is an endocrine disease that is very common in older horses, affecting up to 76% of the geriatric population.


The condition is due to over-activity of the pituitary gland (a gland located beneath the brain). The pituitary gland becomes enlarged and produces excessive quantities of hormones. The hormones known to be of importance include: ACTH, endorphins and melanocortins, but there are many others produced. The disease progresses, gradually becoming worse over time.


Clinical signs


  • Hirsutism is the term for excessive hair growth or abnormal retention of the hair coat in the summer and PPID is the only condition that causes this abnormality.


  • Laminitis is the most serious complication of PPID. It can be seen due to changes in metabolic function and the body’s ability to regulate insulin (Insulin Resistance).


  • Muscle wasting may be seen in some cases and is usually most obvious over the hindquarters. A “pot-bellied” appearance is often seen.


  • Increased drinking (polydipsia) and urination (polyuria) may occur in up to a third of horses with PPID; the reasons for this are unknown


  • Increased sweating (hyperhidrosis) may be seen even in horses that don't have an excessively long haircoat.


  • Lethargy or a more docile temperament may be observed and usually resolves with treatment.


  • Infectious disease occurs more commonly in horses with PPID compared to normal horses of the same age because some of the hormones released with the condition suppress the immune system. Common infections include ringworm, sinus infection, pneumonia, and foot abscesses. Horses with PPID are also more likely to have infections without showing clinical signs and have been shown to be more susceptible to parasites.




A diagnosis can be made from clinical signs and blood tests (endogenous ACTH).




Fortunately, effective treatment for PPID is available in the form of pergolide. Pergolide is available as an oral liquid or oral tablet (that can be dissolved and mixed in feed). It must be given once daily for the rest of the horse/pony’s life. A positive response to treatment includes an improvement in demeanor, coat condition, body condition, and laminitic state, and is usually seen within 6-12 weeks of beginning treatment.


Horses with PPID require extra attention with regard to dental care, hoof care and parasite control. With good management, there is no reason why horses with PPID cannot live a long and normal life and continue in normal work.