LABORATORY DIAGNOSIS OF EQUINE PITUITARY PARS-INTERMEDIA ADENOMA

The objective of the study was to determine the sensitivity with which an adenoma of the pars intermedia of the pituitary gland can be predi cted in horses by measuring the basal plasma concentrations of glucose , cortisol, adrenocorticotropin (ACTH), and insulin, the urinary conce ntration of corticoids, the urinary corticoid:creatinine ratio, and th e plasma cortisol concentration after the administration of 25 IU of A CTH(1-24) intravenously. The records of 24 cases of histologically con firmed equine pituitary pars intermedia adenomas were used. An adenoma of the pars intermedia of the pituitary gland in horses was predicted with a sensitivity of 100, 100, and 92% for basal plasma ACTH (n = 16 ), the urinary corticoid:creatinine ratio (n = 7), and basal plasma in sulin (n = 12), respectively. The sensitivity of the ACTH-stimulation test was 79% (n = 14).