An 8 week-old female, intact Cavalier King Charles Spaniel was presented to Cornell University Hospital for Animals (CUHA) Soft Tissue Surgery Service on March 30, 2017 for surgical correction of a patent ductus arteriosus (PDA). An echocardiogram was previously performed on 3/22/17 by CUHA’s Cardiology Service, which revealed turbulence in the main pulmonary artery and aorta, and confirmed the presence of a PDA. It also revealed an enlarged left atrium and ventricle, likely a secondary change due to persistent volume overload. The patient was started on pimobendan to decrease left heart pressures. Owners reported no other concerns.

On presentation, the patient was bright, alert, and responsive and her vital parameters (temperature, heart rate, and respiratory rate) were within normal limits. She had a V/VI, continuous murmur with a palpable precordial thrill that was best heard at the left heart base. Her mucous membranes were light pink with a capillary refill time of one second and she had bounding femoral pulses on palpation. The remainder of her general physical exam was unremarkable. Her main problem list includes her grade V/VI continuous murmur and hyperkinetic pulses.

The top differential for the patient’s presentation is a patent ductus arteriosus. A PDA is a structural anomaly that results when the ductus arteriosus, a normal fetal structure, fails to close after birth. It is one of the most common congenital cardiovascular abnormalities in dogs. During fetal life, the ductus arteriosus shunts blood from the pulmonary circulation to the systemic circulation, bypassing the non-functioning fetal lungs. Expansion of the lungs after birth causes a profound decrease in pulmonary vascular resistance. In the presence of a PDA, the high systemic pressures and low pulmonary artery pressures causes blood to flow from the aorta to the pulmonary artery, causing a volume overload of the pulmonary vasculature and the left-side of the heart. This additional flow through the pulmonary circulation causes the heart and pulmonary vasculature to remodel itself in response to the increased volume load. Left-sided congestive heart failure is a common sequella of PDAs, and progression to generalized heart failure is possible if left untreated.

This report will discuss the anatomy and pathophysiology of PDAs and focus on the different treatment options and their prognosis.