[Severe cardiac malformation with secondary polycythemia in a 5-month old calf].

A 5-month old female Red-Holstein calf in poor condition was presented with a history of reduced appetite, respiratory disease and collapse. Clinical examination revealed an elevated heart rate and pronounced cyanosis of the mucous membranes. Heart and lung auscultation were normal. A complete blood count revealed profound polycythemia with severely increased values for packed cell volume, hemoglobin concentration and erythrocyte count. Cardiac ultrasonography revealed abnormal position of the great vessels with two arteries located in the right ventricle output tract and a high ventricular septum defect (VSD). Intracardial pressure and blood gas measurements confirmed pressure overload in the right heart, a left-to-right shunt through the VSD and a right-to-left-shunt leading to hypoxemia and secondary polycythemia. Based on poor prognosis, the animal was euthanized. Post-mortem examination confirmed the results of the further investigations conducted to determine the cause of polycythemia in this calf.