Patent Ductus Arteriosis in Dogs

The ductus arteriosus is an important blood vessel that makes sure that blood does not go into the lungs of the fetus in the uterus. It allows the blood of unborn puppies to bypass the lungs (which are not mature enough to function). The oxygen is received from the mother. The vessel closes off after birth, this allows blood to travel normally through the lungs for oxygenation.  If the ductus arteriosus does not close it causes blood to be diverted in abnormal patterns throughout the heart. 

Patent ductus arteriosus (PDA) is the second most common congenital heart defect in dogs. The breeds that PDA most commonly affects are Collie, Miniature Poodle, Shetland Sheepdog, Maltese, Bichon Frise, Chihuahua, German Shepherd, Pomeranian, Cocker Spaniel, and Labrador Retriever. When patent ductus arteriosus is left untreated it may lead to congestive heart failure and high blood pressure, and it can be fatal.

The ductus arteriosus is a blood vessel that connects the aorta and the pulmonary artery of a fetus.  The ductus arteriosus closes shortly after birth; in puppies with patent ductus arteriosus (PDA), this passageway remains open.

In most cases, patent ductus arteriosus is usually diagnosed by a veterinarian during the puppy’s initial wellness examination. Veterinarians routinely will listen to a puppy’s chest with a stethoscope; with PDA your veterinary caregiver will hear a loud, constant heart murmur.  Pet owners of affected dogs will rarely notice any symptoms of patent ductus arteriosus. When symptoms do become apparent, they are usually signs of congestive heart failure and may include one or more of the following:

• Weakness
• Tires easily from exercise
• Palpable heart murmur
• Fatigue
• Cough
• Respiratory distress
• Seizures
• Collapse

Most veterinary cardiologists consider patent ductus arteriosus an inherited disorder.  PDA may also be influenced by other factors that include:

• Infections
• Malnutrition
• Environmental 
• Pharmaceuticals
• Toxicological

The veterinarian will go over your pet’s medical history.  He will ask you what symptoms you have observed and when did they first commence. The veterinarian will perform a physical exam on your dog.  He will listen to your pet’s heart using a stethoscope.  With patent ductus arteriosus, the veterinarian will hear the sound of a heart murmur. Diagnostic tests that your veterinarian may suggest are: 

• A cardiac ultrasound evaluates the speed of blood flow through the patent ductus arteriosus and determine the pressures in the heart chambers
• X-rays of the chest can show the size of the heart and vessel and will also show if there is fluid in the lungs
• An electrocardiogram (ECG) helps identify any dilation or hypertrophy of the heart chambers
• Blood work may be suggested to rule out any bacterial infections or anemia

Your pet will need to be sedated for these tests.

The main objective in treating patent ductus arteriosus is to close the ductus arteriosus and have normal blood flow in the heart chambers.

When patent ductus arteriosus is caught and treated early, the prognosis for dogs to live a normal life is very good. Canines that have developed congestive heart failure due to patent ductus arteriosus may have higher surgical risks.  Preoperative procedures for canines with congestive heart failure may include the use of vasodilators and diuretics. Diuretics will help with fluid retention and vasodilators can help with high blood pressure, both common symptoms of congestive heart failure.

Surgery will be performed by veterinarian cardiologist. He may choose to tie off the vessel by open heart surgery called thoracotomy or through cardiac catheter occlusion. The catheter closes the duct with coils or a ductal occluder. Both procedures are performed under general anesthesia.

Usually your pet will have to stay hospitalized for a few days after surgery.  When your pet is released, the veterinary surgeon will give you a specific post-operative treatment plan. It is important to keep any bandages dry and clean. Your pet’s activities and exercise will be limited for a few weeks after the surgery. It is important that he gets plenty of rest and stressful situations must be avoided. An Elizabethan collar (cone) will help prevent your pet from licking or biting at the incision. The veterinarian may suggest a low sodium diet for your dog. 

Follow-up visits will be needed, to check on your pet’s progress and to remove sutures. Commonly, a repeat echocardiogram is suggested within a few months after the surgery. If there was any permanent damage to the heart there will be additional check-up appointments. Most dogs will have a normal lifespan following the PDA surgery.