PROBLEMS IN THE DIAGNOSIS OF PITUITARY-ADENOMA (CUSHINGS-SYNDROME) INHORSES

Thyrotropin releasing hormone (TRH) stimulation tests were carried out on a number of horses, including one clinically affected horse whose age and clinical signs suggested that a pituitary adenoma was most unl ikely. The results of these tests indicated that, according to criteri a published overseas, the majority of these horses had pituitary adeno mas. The fact that clinically normal or affected horses may have marke d increases in cortisol concentrations indicates that the TRH stimulat ion test is not suitable for the diagnosis of pituitary adenoma. Other tests, including alterations in glucose metabolism and, if available, ACTH measurements, are probably more useful for diagnosis. However, m ost diagnoses will probably rely upon the characteristic clinical sign s.