Variation in plasma adrenocorticotropic hormone concentration and dexamethasone suppression test results with season, age, and sex in healthy ponies and horses

Abstract

The purpose of this study was to evaluate the variation in plasma adrenocorticotropic hormone (ACTH) concentration and dexamethasone suppression test (DST) results with season, age, and sex in healthy, pony mares (n = 15) and pony stallions (n = 14) living under semiferal conditions and horse mares (n = 10) living at pasture. Plasma ACTH concentrations were measured in September 2002, and in January, May, and September 2003. DSTs were performed in January and September 2003. Plasma ACTH concentrations in September 2002 and September 2003 were similar and were significantly greater than in January and May (P.05). Seasonal changes in plasma ACTH concentration and DST results should be considered when interpreting endocrine test results. Copyright © 2005 by the American College of Veterinary Internal Medicine.