The efficacy of L-Deprenyl in dogs with pituitary-dependent hyperadrenocorticism

Ten dogs with pituitary-dependent hyperadrenocorticism (PDH) received 2 mg/ kg of L-Deprenyl once daily for 6 months. Monthly patient assessment consis ted of evaluation of the owner's daily observation protocol, a standardized owner questionnaire, physical examination, CBC, biochemical profile, deter mination of the urine coaisol/creatinine ratio (UC/C), low-dose dexamethaso ne suppression (LDDS) test, corticotropin releasing hormone (CRH) test, and adrenal ultrasonography. At the beginning and the end of the study, an adr enocorticotropic hormone (ACTH) stimulation test and computed tomography al so were performed. Two dogs developed neurologic signs and 2 dogs developed acute pancreatitis. An increase in activity, decrease in polyphagia, and d ecrease in panting were reported by 6, 4, and 2 owners, respectively. Seven owners believed that water intake decreased, but this was confirmed in onl y 3 dogs. Water intake increased in 2 dogs and remained unchanged in 5 dogs . The condition of the hair coat and skin improved in 2 dogs, worsened in 3 , and remained unchanged in 5. Urine specific gravity, urine osmolality, AC TH test results, UC/C, and adrenal gland size did not change significantly throughout the study. In 4 of 8 dogs, LDDS was abnormal at the start of the study but normal at the end of the study, and in 2 dogs, the opposite occu rred. Marked individual variation was noted in the CRH test, with a tendenc y for smaller increases in ACTH toward the end of the study. A marked incre ase in hypophyseal tumor size occured in 4 dogs. Treatment with L-Deprenyl resulted in improvement, deterioration, and stagnation of clinical signs in 2, 4, and 4 dogs, respectively. The results of this study indicate that L- Deprenyl cannot be recommended as the sole treatment for canine PDH.