Rupture of the left aortic sinus into the pulmonary artery in a Dalmation dog.

An 18-month-old male Dalmatian dog was presented for veterinary evaluation after the pet owner observed a sudden onset of weakness. An acquired continuous cardiac murmur was detected on physical examination. Two-dimensional echocardiographic examination revealed structural abnormalities of the proximal aorta and pulmonic valve. Doppler echocardiographic studies and cardiac catheterization demonstrated the presence of a proximal aorticopulmonary shunt. A diagnosis of left aortic sinus rupture and aorticopulmonary fistula was made. Antemortem diagnosis of aortic sinus rupture in the dog has not, to our knowledge, been reported previously. The anatomical variant of left aortic sinus rupture resulting in the development of a fistula from the aorta to the main pulmonary artery is, apparently, uncommon in all species.