Patent ductus arteriosus (PDA) is a congenital heart defect where a fetal blood vessel (ductus arteriosus) fails to close after birth. This vessel, which connects the aorta and pulmonary artery, allows blood to bypass the lungs while the fetus receives oxygen from the placenta. When a puppy takes its first breath, the ductus normally closes, ensuring blood circulates through the lungs for oxygenation. However, if it remains open, or “patent,” blood is redirected from the aorta back into the pulmonary artery, leading to increased workload on the heart. Over time, this can result in heart enlargement, congestive heart failure, or even reverse PDA. PDA is more common in female dogs and certain small breeds (Maltese, Pomeranians, and Shetland Sheepdogs). The diagnosis typically occurs when a veterinarian detects a loud heart murmur during an exam. Chest x-rays and an echocardiogram can confirm the diagnosis. Treatment includes surgical closure of the duct with a high success rate if treated early.
