A patent ductus arteriosus is one of the most common heart defects that dogs are born with. The ductus arteriosus is a normal fetal structure that connects the aorta and pulmonary artery (two large blood vessels that carry blood to the body and lungs). After birth, the ductus arteriosus is no longer needed and will naturally close. In some puppies (and less commonly kittens) the ductus arteriosus remains open (patent).
Why is this a problem?
In normal circulation, the aorta and pulmonary artery are separate blood vessels. The aorta delivers oxygen rich blood to the body and the pulmonary artery delivers oxygen depleted blood to the lungs. A PDA allows for a persistent connection between these two large vessels. The end result is excess blood circulating to the left heart chambers causing left heart enlargement. The majority of dogs with a PDA will develop left sided congestive heart failure if the PDA is not closed.
How is it diagnosed?
Most young puppies are asymptomatic but a murmur is detected on a routine puppy examination by your veterinarian. The murmur is usually loud and has a characteristic sound (often described as a ‘washing machine’ murmur). Imaging is still necessary for official diagnosis. X-rays are useful to examine the heart size and look for fluid in the lungs. An echocardiogram (ultrasound of the heart) is the most sensitive test that allows the veterinary cardiologist to diagnose the PDA.
What is the prognosis?
Approximately 60% of dogs with a PDA with develop congestive heart failure before they reach a year of age. Therefore, early diagnosis and closure of the PDA is essential to prevent permanent heart damage. Treatment involves one of two procedures:
Surgical Ligation: Open chest surgery to place sutures around the ductus arteriosus. This procedure is more successful when performed by a board certified surgeon.
Transvenous Catheterization: Minimally invasive catheter technique to place a device within the ductus arteriosus. This procedure is done by a veterinary cardiologist and requires specialized equipment. If your dog is small (less than 6 pounds) than he/she may not be a candidate for this type of procedure.
Puppies that have their PDA closed have a great prognosis and typically live a normal lifespan. A recheck echocardiogram is done 1-2 months after closure to evaluate heart size and function. For most cases, the heart will return to near normal in size and no long term medications are needed.
