Diabetes insipidus and hyperadrenocorticism associated with high plasma adrenocorticotropin concentration and a hypothalamic/pituitary mass in a dog.

Central diabetes insipidus was diagnosed in association with a dexamethasone-insuppressible adrenocorticotropin-secreting tumor in a dog. Over the 3 years before the dog's death, the combination of specific pituitary function tests, peptide hormone radioimmunoassays, and visualization of the tumor by use of x-ray computed tomography of the skull, allowed an etiologic diagnosis. Because initial signs of glucocorticoid excess were questionable and adrenolytic therapy was not allowed by the owners, treatment consisted only of administration of synthetic vasopressin, which was successful in the management of the diabetes insipidus.