Congenital quadricuspid aortic valve anomaly in two dogs.

A congenital quardricuspid aortic valve (QAV) was detected in two one year-old male dogs. This defect has not previously been reported in dogs. In both cases, the diagnosis was made by two-dimensional echocardiography performed to investigate the cause of a soft heart murmur. On the short-axis of a two-dimensional echocardiogram, the commissures of the QAV produced an "X" configuration of the valve during diastole in contrast to the "Y" configuration observed in dogs with a normal semilunar valve. Color flow Doppler studies indicated mild aortic regurgitation in both dogs, neither of which evidenced signs of disability. Subsequent necropsy of one of the dogs confirmed the presence of QAV.