Absolute Erythrocytosis in a Sunda Wrinkled Hornbill (Aceros corrugatus)

A captive, 22-year-old, intact male Sunda wrinkled hornbill (Aceros corrugatus) was presented for an acute onset of open-mouth breathing and bilaterally drooped wings. An external physical examination revealed a moderately thin body condition, marked respiratory effort, and a significant heart murmur. Diagnostic blood testing revealed moderate azotemia and persistent erythrocytosis, initially documented 2 years before this event. Radiographic imaging revealed a subjectively enlarged heart and a right dorsal coelomic cavity mass. Further diagnostic testing included an echocardiogram and ultrasound-guided fine-needle aspirate of the right coelomic cavity mass, with cytology consistent with a carcinoma. The bird was euthanatized because of the poor prognosis. Necropsy and histopathology identified right atrioventricular valve hypertrophy with severe hypertrophic and dilated cardiomyopathy of the right ventricular free wall, atherosclerosis of the great vessels and arteriosclerosis of myocardial vessels, severe hepatic extramedullary hematopoiesis, and pulmonary carcinoma of the right lung. In this case, erythrocytosis was considered a physiologic response to hypoxemia caused by the lung mass.