Perimembranous Ventricular Septal Defect Concurrent with an Aorto-Right Ventricular Fistula Caused by a Ruptured Sinus of Valsalva in Three Dogs

An aorto-right ventricular fistula, a rare condition in humans, is characterized by communication between the ascending aorta and the right ventricle through a defect in the aortic wall. This report describes three cases of dogs with continuous murmurs: a 6-month-old Coton de Tulear, a 5-year-old Maltese, and a 6-month-old Jindo. Notably, all of the dogs presented with no severe clinical signs. Echocardiography revealed a turbulent jet through restrictive perimembranous ventricular septal defects (VSD) during systole and aorto-right ventricular fistulas secondary to ruptured sinuses of Valsalva aneurysm during diastole. In one case, a surgical closure of the VSD simultaneously resolved the aorto-right ventricular fistula. Follow-up echocardiography in the other two cases revealed mild left heart volume overload and a slight increase in the pulmonary-to-systemic blood flow ratio. However, the dogs remained asymptomatic. In conclusion, aorto-right ventricular fistulas with VSDs should be considered in the differential diagnosis of continuous murmurs in dogs.