Patent ductus arteriosus, or PDA, is a heart defect that occurs when the circulation of blood in a cat or dog’s heart does not change like it should following birth.
The ductus arteriosus is a blood vessel that is important in growing fetuses because it moves blood directly from the heart to the aorta to the body without stopping for oxygen in the lungs (fetuses already get oxygen from their mother’s bloodstream).
Shortly after a puppy or kitten takes their first breath, this blood vessel is supposed to close up, which allows the animal’s blood to begin travelling normally through the pulmonary artery to the lungs for oxygenation. In some animals, however, the blood vessel stays open, and this is what is referred to as patent ductus arteriosus. This condition causes blood to be diverted (shunted) in abnormal patterns through the heart, and can result in life-threatening conditions like high blood pressure and congestive heart failure.
Causes of Patent Ductus Arteriosus in Dogs and Cats
Patent ductus arteriosus is a birth defect caused by a genetic predisposition. Therefore affected dogs and cats should not be bred.
Symptoms of Patent Ductus Arteriosus in Dogs and Cats
As PDA progresses, symptoms of congestive heart failure may begin to appear. Symptoms may include:
Diagnosing and Treating Patent Ductus Arteriosus in Dogs and Cats
Most cases of PDA are discovered when a seemingly healthy puppy or kitten is taken to the veterinarian for a routine check-up and a heart murmur is detected. A heart murmur is a sound caused by a disturbance of blood flow in the heart, and PDA murmurs have a very distinctive sound.
If a PDA is suspected, the veterinarian may order certain tests to confirm the diagnosis, including an x-ray, electrocardiogram (evaluates heart’s electrical activity), and echocardiogram (cardiac ultrasound). An echocardiogram is the most common type of test used for diagnosing a PDA because it allows the veterinarian to see a real-time image of heart’s activity.
Most pets diagnosed with patent ductus arteriosus will require surgery to close the ductus arteriosus, and surgery is usually performed as soon as possible. Pets who are not immediately treated often die of congestive heart failure. If the pet is already suffering signs of congestive heart failure, they will be stabilized before surgery is performed.
There are two surgical options:
Thoracotomy, or open-chest surgery. This is an invasive surgery but most pets recover well and only feel pain for 1 to 2 days following the procedure. The pet may need to be hospitalized during recovery and sutures are removed 7 to 10 days after surgery.
Cardiac catheter-based occlusion. This is a minimally-invasive procedure that involves closing the open duct with coils or a ductal occluder. Pets often go home the following day and sutures are removed 7 to 10 days later.
The prognosis for PDA is generally good if the defect is detected and surgically corrected before the pet succumbs to congestive heart failure. Pets successfully treated with surgery usually go on to live normal, healthy lives, though follow-up testing and examinations may be required. Always keep up with your pet’s routine physical exams so that problems like PDA can be detected before they progress too far.
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