Subaortic stenosis and mitral dysplasia in three Black Russian Terrier puppies

A combined congenital heart defect of aortic stenosis and mitral dysplasia was diagnosed in three Black Russian Terrier puppies two months old. The aortic stenosis component included both fixed and dynamic obstructions. The fixed obstruction was subvalvularly located at the entrance to the left ventricular outflow tract. The dynamic obstruction was caused by the septal leaflet of the mitral valve protruding into the left ventricular outflow tract. Mitral dysplasia resulted in mitral insufficiency leading to regurgitation through the mitral valve closer to the septal side. The maximum pressure gradient across the aortic valve amounting to 103 mmHg measured in one puppy was consistent with the most severe grade of stenosis. The diagnosis was confirmed by autopsy in all three puppies that were males and originated in one litter, so genetic influences are supposed.