Unilateral absence of the right pulmonary artery with associated aortopulmonary collaterals and bullous lung lesions in a dog

This case report describes a combination of congenital cardiopulmonary abnormalities found in a 1-year-old Labrador Retriever. To the authors' knowledge this combination of cardiopulmonary abnormalities has not been previously reported in veterinary medicine. Unilateral absence of the right pulmonary artery associated with unilateral right-sided aortopulmonary collaterals was observed. These aortopulmonary collaterals preserved the blood supply to the right lung lobes but led to left ventricular volume overload. There was also evidence of severe bullous lung disease in the right lung, which was suspected to be secondary to pulmonary sequestration as a result of the anomalous hemi-pulmonary circulation. The diagnosis of left-sided volume overload was achieved by radiography and echocardiography while the remainder of the findings was diagnosed on computed tomography angiography. The owner refused surgery for occlusion of the shunting vessels and therapy at standard doses of benazepril, spironolactone and pimobendan was initiated. In spite of the severe volume overload, the dog remained stable with static non-progressive clinical signs and stable echocardiographic findings at 1-year follow-up. The case report also acts as a reminder of the possible occurrence of unusual extra-cardiac shunts in the presence of an unexplained left ventricular volume overload.