A case of norepinephrine secreting pheochromocytoma in a dog

An-11-year-old male Shih-tzu was admitted to emergency care unit of Haemaru Referral Animal Hospital with signs of dyspnea, anuria and depression. There were abnormalities on complete blood count and serum chemistry included leukocytosis with mild left shift, mild azotemia, and increased ALT activity. Fluid therapy (0.9% saline, 40 ml/ hr) and antibiotics were immediately initiated. The patient began to vomit after 5 hours' rest and pale mucous membrane, bradycardia, and hypertension were noted. Abdominal ultrasonography revealed enlarged left adrenal gland and thrombus in caudal vena cava (CVC). Result of ACTH stimulation test was normal. Cytology of ultrasound-guided FNA smears showed numerous naked nuclei, which was suggestive of adrenal medullar tumor. Concentrations of 24 hour urine metanephrine and normetanephrine was moderately increased compared to those of a control dog. Adrenal mass was surgically removed, and biopsy of the CVC mass was obtained. After surgery the patient began to recover but the dog acutely developed cardiopulmonary arrest and died. On histopathology the adrenal mass and biopsy of the CVC mass were consistent with pheochromocytoma. On electron microscopic view norepinephrine specific granules were found in the cytoplasm of tumor cells.