Pituitary Pars Intermedia Dysfunction.

Pituitary pars intermedia dysfunction (PPID) is one of the most common equine endocrine disorders. It is caused by oxidative damage to dopaminergic neurons in the hypothalamus and results in loss of inhibition of the pituitary pars intermedia. This leads to increased circulating concentrations of adrenocorticotropic hormone (ACTH) and related peptides. Diagnosis is based on increased resting and/or thyrotropin releasing hormone-stimulated ACTH concentrations. Assessment of insulin regulation is also important, as insulin dysregulation occurs in at least one-third of PPID cases and is associated with laminitis risk. Management requires treatment with the dopamine agonist pergolide and an appropriate diet.