Patent Ductus Arteriosus in Dogs

Patent Ductus Arteriosis, or PDA, is the most common congenital heart defect in dogs. Some breeds, including poodles, collies, German shepherds and Chihuahuas are more prone to the condition, and it is more common in female dogs than in males. If left untreated, PDA has a 60 percent mortality rate.

  1. Ductus Arteriosis

    • The ductus arteriosis is a blood vessel found in puppies before they are born. This vessel closes within a few days of birth in most puppies, allowing the blood to begin flowing through the lungs. In puppies with patent ductus arteriosis, the vessel does not close, resulting in abnormal blood flow between the aorta and pulmonary artery. This, in turn, results in an increase in the amount of blood that flows through the left side of the heart, causing that side to work harder. The increased volume of blood and extra work for the left side of the heart can cause heart failure.

    Diagnosis and Symptoms

    • Blood that flows through an unclosed ductus arteriosis causes a heart murmur, which your vet will usually hear on your puppy's first examination. Your vet may then get X-rays of your puppy's chest to detect enlargement of the heart. An echocardiogram is required to get a firm diagnosis.

      Some dogs with PDA may suffer symptoms such as lack of tolerance for exercise, coughing and breathing difficulties. Other dogs may show no clinical signs at the time of diagnosis.

    Interventional Catheterization

    • Two major treatment options are available for dogs with PDA. The first is interventional catheterization. This is a minimally invasive procedure in which the vet advances a catheter from the artery in the right inner thigh to the aorta and then into the ductus arteriosis. He injects dye into the vessel to determine the size and shape, then places a coil, plug or device called a canine duct occluder into the ductus arteriosis to stop blood flow through it and restore normal blood movement in the heart.

      A dog must weigh at least 4 to 5 lbs. to be eligible for catheterization. If the PDA is small and the puppy is not showing clinical signs of major heart changes, your vet may wait until the puppy reaches the proper weight to perform the procedure.

    Surgical Ligation

    • In some instances, the PDA may be a shape that prevents the use of interventional catheterization, and your vet may perform surgical ligation instead. She will make an incision in the left side of the chest to expose the heart, then tie off the ductus arteriosis to stop the abnormal blood flow.

      Both interventional catheterization and surgical ligation will take an average of two hours to complete.

    Complications

    • Complications of interventional catheterization and surgical ligation include rupture and bleeding of the PDA or the artery in the leg, incomplete blockage of the ductus arteriosis, a blockage device embolizing to the lungs and puncture of the heart or blood vessels. Occasionally, residual air in the thoracic cavity may require insertion of chest tubes.