Non-functional equine pheochromocytoma: case report

ABSTRACT An 8-year-old gelding athlete used for barrel racing was admitted to the veterinary hospital for poor performance, recurrent anemia, intermittent fever, and an episode of abdominal discomfort. The first clinical signs appeared 45 days before admission. On physical examination, the animal presented tachycardia, tachypnea, and jaundiced mucous membranes. The blood count revealed anemia and leukocytosis due to neutrophilia. On the sixth day of hospitalization, the horse again showed signs of abdominal discomfort. Ultrasonography revealed two neoplastic masses: one located cranially to the right kidney, in the retroperitoneal space, and the other ventral to the same kidney, in the peritoneal cavity. Image-guided cytology of the cranial mass was performed, and the cytopathological examination revealed chromaffin cells compatible with pheochromocytoma. Videolaparoscopy allowed the visualization of only the ventral mass to the right kidney, with a granulomatous surface adjacent to the duodenum, without clear definition of its origin and extent. There were signs of inflammation in the small intestine and in the peritoneum near the neoplasm. The horse was treated symptomatically during hospitalization, with no recurrence of clinical signs and two years after the initial referral, it had returned to the same level of sports activity. The case was classified as non-functional pheochromocytoma.