Feline Pituitary-Dependent Hyperadrenocorticism and Insulin Resistance Due to a Plurihormonal Adenoma

A 12-year-old female spayed domestic short-haired cat presented for lethargy, poor hair coat, alopecia, difficulty walking, and mild polyuria/polydipsia. The cat's skin tore easily in the neck area during routine restraint for blood draw. Physical examination, blood analysis, and ultrasound imaging were all consistent with pituitary-dependent hyperadrenocorticism (PDH) with secondary insulin-resistant diabetes mellitus, which was nonketotic. Insulin therapy, fluids, and diet change were initiated for the diabetes mellitus and the owner reported improvement in clinical signs although the blood glucose measurements remained elevated. Surgical repair of the torn skin was successful. Although a guarded prognosis was given to the owner because of an advanced stage of hyperadrenocorticism, and the limited treatment options currently available for feline PDH, trilostane was agreed on as an initial therapeutic option. The day trilostane was to be initiated, the cat presented with dyspnea and the owner chose to euthanize. Because of the rarity of hyperadrenocorticism disease in the cat, permission was obtained by the owner for a necropsy to confirm suspected PDH as the underlying cause for insulin resistance and skin fragility syndrome.