Equine Image Quiz: A pony with polydipsia and forelimb lameness

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Aug 03, 2010
By dvm360.com staff

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A dexamethasone suppression test may confirm a presumptive diagnosis of pituitary pars intermedia dysfunction, otherwise known as PPID or Cushing's disease. PPID is an endocrine condition in horses characterized by pituitary dysfunction and excess production of ACTH and other pituitary-derived hormones and, subsequently, cortisol. The pituitary gland condition is attributed to hyperplasia or adenoma formation of the pituitary pars intermedia as a result of oxidative damage to dopaminergic neurons in the hypothalamus that normally regulate the intermediate lobe of the pituitary gland. Common clinical signs include inappropriate hirsutism, weight loss, poor performance, polyuria, polydipsia, recurrent laminitis, increased incidence of secondary opportunistic infections, and pendulous abdomen. PPID is chronic and progressive. Treatment of PPID involves a combination of management changes and medical treatment with pergolide.