Pituitary Pars Intermedia Dysfunction

Photo credit: The Independent

Pituitary Pars Intermedia Dysfunction (PPID), also called equine cushiness disease is a disease that affects the pituitary gland in horses and ponies. PPID is also linked to laminitus.


  • nerves to the pituitary gland degenerate, leading to enlargement of the pituitary and the production of excessive quantities of hormones.
  • as nerves continue to degenerate, the disease progresses and the gland is considered over active.

Clinical signs:

  • Disease affects over 25% of horses over the age of fifteen years and is more commonly found in ponies with risk increasing with age.
  • Hirsutism – excessive hair growth and retention of hair coat in the summer. This is the most reliable indicator of PPID.
  • Polydipsia and polyuria – excessive drinking and urinating.
  • Hyperhidrosis – excessive sweating
  • Infertility in mares. This is caused by changing levels of hormones affecting fertility.
  • Infections – horses with PPID are more likely to develop infections, such as ringworm, as a result of certain hormones which suppress the immune system being produced excessively.
  • Abnormal fat deposits particularly around the eyes (periorbital deposits).
  • insulin resistance


An ACTH test is used to diagnose PPID. This tests for the presence of the adrenocorticotrophic hormone.


Pergolide is used as a treatment. Interestingly, this drug can also be used to treat Parkinson’s disease in humans.

The drug is a dopamine receptor agonist. In a healthy horse, there is plenty of dopamine and when dopamine binds to dopamine receptors it inhibits the production of chemicals. Pergolide acts as dopamine and binds to dopamine receptors, hence stopping excessive production of hormones.




  1. https://www.vettimes.co.uk/news/vets-should-routinely-test-older-horses-for-ppid/
  2. http://www.nadis.org.uk/bulletins/pituitary-pars-intermedia-dysfunction-(equine-cushing’s-disease).aspx?altTemplate=PDF
  3. https://www.talkaboutlaminitis.co.uk/ppid
  4. https://en.m.wikipedia.org/wiki/Pergolide

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