Clinical and postmortem findings of pentalogy of Fallot in an 18-month-old Holstein heifer.

An 18-month-old female Holstein Friesian heifer presented with a history of stunted growth and a recent onset of anorexia; she presented with cyanosis and eventually died. A postmortem examination revealed obstruction of the right ventricular outflow tract, ventricular septal defect, overriding aortic root, right ventricular hypertrophy, and an atrial septal defect, indicating a pentalogy of Fallot (POF). In addition to POF, the heifer also had pulmonary artery dilatation, although she did not present with patent ductus arteriosus. This heifer had the longest lifespan among the Holstein cattle reported to have POF, which may be secondary to delayed pulmonary obstruction due to deformation of one of the pulmonary valves.