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Patent Ductus Arteriosus

General Information

The developing fetus within the womb does not use its own lungs to mix blood and oxygen. Instead, it receives oxygen-rich blood from its mother through placental circulation. A blood vessel (the ductus arteriosus) in the unborn fetus bypasses the lungs to send blood to the rest of the body. Only a small amount of fetal blood flows through the lungs.

Normally, the ductus arteriosus closes within a few hours of birth. In some animals, the bypass does not close, and blood continues to bypass the lungs and not pick up oxygen. A human infant with patent ductus arteriosus is called a "blue baby."

This defect occurs more in Poodles, Collies, Pomeranians and Shetland Sheepdogs than other breeds. Many affected pups die of heart failure within the first few weeks of life, but most pets that live to 8 weeks of age survive into adulthood. When the bypass is small, the dog may live a normal life without ever showing any ill effects. Patent ductus arteriosus also occurs in cats.

What is Patent Ductus Arteriosus (PDA)?

The ductus arteriosus is a blood vessel that connects the two main arteries of the body -- the aorta and the pulmonary artery. This blood vessel is normal in the fetus, but at birth, the vessel should close. When the ductus arteriosus is persistently open (patent) after birth, extra blood can flow into the blood vessels of the lungs. The resulting condition poses a serious health problem to your pet.

What Causes PDA?

This condition is the second most commonly diagnosed congenital heart defect of dogs. It affects about 7 out of every 1000 puppies. The condition is usually inherited as a genetic trait. PDA is less common in cats.

What are the Signs of PDA?

Affected puppies initially appear normal, although they are usually smaller and play less vigorously than their littermates. Typically there are no clinical signs until congestive heart failure develops. This leads to fluid accumulation in the lungs that causes coughing and difficulty breathing. In most cases, clinical signs develop within a year. About 60% of affected dogs will die without surgical treatment.

How is PDA Diagnosed?

Many puppies with PDA are diagnosed when they are presented to a veterinarian for their initial puppy check up or vaccinations. PDA is identified by examining the heart with a stethoscope and by detecting a characteristic heart murmur. Since a heart murmur can be present with other disorders, a definitive diagnosis may require additional tests including chest X-rays, electrocardiogram (ECG or EKG), and ultrasound examination of the heart (echocardiography).

How is PDA Treated?

Treatment consists of an operation that is done as soon as possible after diagnosis. The operation requires general anesthesia and an incision in the chest (thoracic surgery). The PDA is located and closed with a surgical suture. In some referral centers, the PDA may be closed using special catheterization techniques, where the chest is not opened, but these are still considered experimental.

There is no benefit to delaying surgery. In fact, the chance of a dog developing heart failure or suffering irreversible damage to the heart muscles only increases with passing time. One should not wait for signs to develop. Should signs (coughing, difficult breathing) already be present, a brief period of medical treatment may be needed to stabilize the puppy's condition before surgery. Following surgery, medications are given to control post-operative pain. After a 1 to 3 day post-operative hospital stay, the dog is released to your care at home.

What is the Prognosis for Dogs with PDA?

The prognosis is very good if surgery is performed early. With prompt recognition and surgical repair there is a 92 to 95% success rate. Following successful surgery, the dog should live a normal life. Unless there are complications from other heart defects, or heart failure has already developed, there is rarely a need for any future medicine or exercise limitations. Without surgery, about 60% of the dogs diagnosed with PDA will die within one year of diagnosis. Of course, there may be special circumstances that can influence the prognosis in an individual case. Any concerns or questions should be discussed with your veterinarian.

Important Points in Treatment

1. Surgical closure is the only means of correcting patent ductus arteriosus. Medical therapy helps stabilize animals in heart failure only for short periods.

2. Your doctor will discuss the advisability of surgery.

3. Activity: Restricted activity is essential for ____ days after surgery. Do not allow running, jumping, ballchasing, or rough playing. Activity may be gradually increased after this time.

4. Diet: Follow the instructions checked.

____Feed the normal diet.

____A special diet is required. Feed as follows:

5. Incision: Check the incision at least twice daily. Report any abnormalities to the doctor. Your pet will be evaluated for suture removal on:


Notify the Doctor if Any of the Following Occur:

* Your pet refuses to eat or is depressed.

* Your pet coughs or has trouble breathing.

* Your pet irritates the incision.

* The incision is red or swollen, or oozes fluid or pus.

* You cannot give the medication as directed.

The majority of the information in this page is has been taken from VetMedCenter.com. For further information about this useful source of informtion follow the link or look, on the internet, at www.vetmedcenter.com.