Paraganglioma, pituitary adenoma, and osteosarcoma in a dog.

An 11-year-old neutered male Alaskan Malamute mixed-breed dog was presented with a complaint of polyuria/polydipsia (PU/PD), weight loss, tachypnea, regurgitation, and a previous history of nontreated osteosarcoma of the right distal radius, diagnosed 21 months prior. On physical examination, an abdominal mass was palpated. The abdominal mass was aspirated and cytologically diagnosed as a neuroendocrine tumor, suspected to be a pheochromocytoma. Laboratory examination revealed a mild anemia and thrombocytopenia, markedly elevated ATP and ALP activities, and moderate hypercalcemia. A low-dose dexamethasone suppression test and endogenous adrenocorticotropic hormone (ACTH) concentration were compatible with pituitary hyperadrenocorticism. On urinalysis, proteinuria was noted as well as a high urine metanephrine/creatinine ratio, consistent with a diagnosis of pheochromocytoma. The dog was treated with supportive care and euthanized 6 months later due to decreasing quality of life. On necropsy, an extra-adrenal pheochromocytoma (paraganglioma) was diagnosed in the caudal abdomen, and a pituitary adenoma and an osteosarcoma of the right distal radius were confirmed.