Congenital cardiac disease in dogs.

Aortic stenosis is a heritable cardiac anomaly most common in German Shepherds, Boxers and Newfoundlands, and less common in Pugs, English Bulldogs, Boston Terriers, Fox Terriers, Schnauzers and Bassets. Clinical signs are associated with secondary left-sided heart failure and include coughing, moist rales, exercise intolerance, arrhythmias and a weak femoral pulse. It causes an ejection-type crescendo-decrescendo, systolic murmur best heard on the left side near the elbow. The ECG may be normal or may show signs of left ventricular hypertrophy, including an axis of less than 40 degrees, a QRS complex of greater than 60 seconds in duration, R waves greater than 3 mv in amplitude, ST segment slurring or depression, or T waves of an amplitude greater than 25% of that of R waves. A LAT radiograph usually reveals an enlarged cardiac silhouette, loss of the cranial cardiac waist, and normal pulmonary vasculature, while DV projections show an elongated cardiac silhouette, rounding of the left ventricular border, and a normal descending aorta. Nonselective angiocardiography reveals poststenotic dilatation of the aorta. Treatment of severely affected dogs involves surgical correction.