Unilateral pulmonary edema in a dog with a large, left-to-right shunting patent ductus arteriosus.

A four-month-old, 5.0-kg male castrated mixed-breed dog was presented for further evaluation of a heart murmur. A grade 6/6 left basilar, continuous heart murmur, and bounding femoral arterial pulses were observed, consistent with a patent ductus arteriosus (PDA). Transthoracic echocardiography confirmed the diagnosis of a large, left-to-right shunting PDA with severe left heart volume overload. Thoracic radiography revealed severe, alveolar lung disease in the right cranial, right middle, and right caudal lung lobes; no pulmonary infiltrate was observed in the left lung lobes. Unilateral pulmonary edema secondary to the PDA was diagnosed, which later resolved with medical management and transcatheter occlusion of the PDA with an Amplatz Canine Ductal Occluder. Unilateral pulmonary edema secondary to a PDA has not been previously reported in the dog.