Domperidone Causes an Increase in Endogenous ACTH Concentration in Horses With Pituitary Pars Intermedia Dysfunction (Equine Cushing’s Disease)

Horses with pituitary pars intermedia dysfunction (PPID) react to domperidone administration with an exaggerated increase in endogenous adrenocorticotropins (ACTH) concentrations. Specifically, a dose of 2.5 mg/kg domperidone orally resulted in an endogenous ACTH concentration in PPID horses that was 2.9 0.68 times baseline values at 4 h post-administration. Endogenous ACTH concentrations in horses without PPID do not exhibit a similar increase. The domperidone-response test represents a promising new evocative test that may prove useful in the diagnosis of PPID in horses. Authors’ addresses: Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, IN 47907 (Sojka, Jackson); and Department of Veterinary Pathobiology, School of Veterinary Medicine, Purdue University, West Lafayette, IN 47907 (Moore, Miller); e-mail: [email protected] (Sojka). © 2006 AAEP.