Patent ductus arteriosus, or PDA, is one of the most common congenital heart defects in dogs. It is a blood vessel that connects the aorta and pulmonary artery during fetal life but should close after birth. When it remains open, the heart becomes overloaded, and without treatment 60–70% of affected dogs die within the first year from heart failure. The good news: PDA is one of the few heart conditions that can be completely cured when detected early.
What Is PDA?
During fetal development the lungs are not functional and gas exchange occurs via the placenta. The ductus arteriosus diverts blood past the lungs directly into the circulation. After birth the lungs expand, oxygen levels rise, and the ductus arteriosus constricts and normally closes within 12–24 hours. In PDA this closure does not happen. Blood flows continuously from the aorta into the pulmonary artery, overloading the left side of the heart and causing it to enlarge. Without treatment this progresses to heart failure.
Predisposed Breeds
PDA has a genetic basis and is more common in females (ratio 3:1). Predisposed breeds include Maltese, Pomeranian, Shetland Sheepdog, English Springer Spaniel, Bichon Frise, Miniature and Toy Poodle, Yorkshire Terrier, Chihuahua and Cocker Spaniel. PDA also occurs in cats but much less frequently.
Signs — What Owners May Notice
PDA is often discovered at the first veterinary visit when the vet hears a continuous "machinery murmur" during auscultation. Owners may notice the puppy is the smallest in the litter, tires quickly during play, breathes faster than normal, or coughs. In more severe cases fainting or abdominal swelling may occur. Sometimes owners feel a vibration on the chest wall when holding their pet.
Treatment
PDA is treated by closing the open ductus. There are two main methods. Surgical ligation is performed via thoracotomy, where the duct is tied off with sutures — success rate exceeds 90–95%. Catheter-based closure (ACDO, Amplatz Canine Duct Occluder) involves delivering a specialized device through the femoral artery to seal the vessel from within — this is less invasive with a success rate over 95–98%. Medical treatment can stabilize the patient before the procedure but does not cure PDA. The earlier the closure is performed — ideally before 6 months of age — the better the prognosis.
Diagnosis at Our Clinic
At Eläinklinikka Saari, we perform cardiac ultrasound examinations that allow us to detect and diagnose PDA at our clinic. Our veterinarian Leena performs the cardiac ultrasound examinations. If a murmur is detected in your puppy, we can examine the heart with ultrasound and refer to a specialist clinic for further treatment if needed.
Prognosis
The prognosis for PDA treated in time is excellent. Dogs whose ductus is closed before heart failure develops typically live a normal life. Heart enlargement often reverses within weeks to months. Without treatment the prognosis is poor: approximately 60–70% of dogs die within the first year.
The Most Important Message for Owners
Every puppy's heart should be auscultated at the first veterinary visit. If a murmur is detected, further examination with cardiac ultrasound should be done without delay. PDA is curable — as long as it is detected in time. Breeders and owners of predisposed breeds should be especially vigilant.