Diagnostic and therapeutic considerations in a hypercalcemic dog with multiple endocrine neoplasia.

Hypercalcemia was found in a dog examined for episodic weakness and disorientation. A right adrenal mass identified on abdominal ultrasonographic examination was diagnosed as a pheochromocytoma based on increased 1231-metaiodobenzylguanidine uptake and characteristic histopathological features. Serum intact parathyroid hormone (iPTH), total serum calcium, and ionized serum calcium were increased prior to surgery. Although both total and ionized serum calcium concentrations decreased to within normal reference ranges following surgery through postoperative day 17, subsequent high concentrations with increased serum iPTH concentrations confirmed concurrent primary hyperparathyroidism. A right parathyroid tumor was suspected based on a technetium-99m-sestamibi (99mTc-sestamibi) scan.