Hyperadrenocorticism and hyperprogesteronemia in a cat with an adrenocortical adenocarcinoma.

A seven-year-old, neutered male domestic shorthair cat was evaluated for poorly regulated diabetes mellitus and increased skin fragility. Imaging studies revealed a right adrenal gland tumor, but cortisol testing did not support a diagnosis of hyperadrenocorticism. Serum concentrations of progesterone and testosterone were increased compared with a group of normal cats, and the clinical signs were attributed to hyperprogesteronemia. At necropsy, a diagnosis of adrenocortical adenocarcinoma was confirmed, and immunohistochemical staining confirmed the presence of progesterone within the tumor. Clinical signs of hyperadrenocorticism in cats may occur due to increased serum concentrations of hormones other than cortisol.