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Overview of Patent Ductus Arteriosus (PDA) in Dogs
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 shortly after birth, it should close. When the ductus arteriosus remains open or patent after birth, this abnormal communication between the aorta and pulmonary artery passes extra volumes of blood into the lungs.
Patent ductus arteriosis (PDA) is a birth defect representing the second most common congenital heart defect of dogs. Approximately seven out of 1000 live birth puppies are affected.
Generally, there are no serious symptoms of PDA unless congestive heart failure has caused fluid buildup in the lungs. The condition is typically identified in puppies during a routine veterinary visit for vaccinations. Continual blood flow through the PDA into the lungs produces a continuous (machinery) heart murmur.
Even when the veterinarian identifies a PDA, most people believe their dog is normal. In some cases, the dog can be smaller than littermates or play less vigorously. However, the situation can be very misleading as symptoms usually occur within a year of diagnosis. If untreated, about 60 percent of affected dogs die within a year of diagnosis.
When caught early, and following treatment with successful closure of the PDA, most dogs live a normal life. Unless there are complications from other heart defects or heart failure has already developed, there is rarely any future need for medication. While special circumstances can influence the prognosis, most cases are straightforward.
PDA is genetically determined in almost every case, and this fact impacts the value of purebred dogs used for breeding. PDA is common in the miniature poodle, collie, Maltese, Shetland sheepdog, German shepherd dog, cocker spaniel, Pomeranian, and Labrador retriever. Female dogs are predisposed.
What to Watch For
Diagnosis of Canine Patent Ductus Arteriosus
Various diagnostic tests are needed to recognize PDA, and exclude other diseases. Some of the necessary tests may include:
Treatment of Canine Patent Ductus Arteriosus (PDA)
Home Care and Prevention
Before any surgery, provide only the exercise your dog can tolerate. Do not allow your dog to become short of breath with activity.
Follow up with your veterinarian after surgery or surgical closure. In most cases, only a suture removal is needed and further follow-up is unnecessary.
There is no way to prevent PDA but dogs diagnosed should not be bred, even if the defect has been corrected.
In-depth Information on Patent Ductus Arteriosus (PDA) in Dogs
Patent ductus arteriosus (PDA) is a common birth defect. The pressure in the aorta is higher than the pressure in the pulmonary artery, therefore, blood crosses the ductus from left (aorta) to right (pulmonary artery). Very infrequently, the increased blood flowing into the lungs injures the pulmonary blood vessels. This can reverse the path of blood flow from right to left. In this case, unoxygenated blood flows into the aorta to the rear limbs, causing weakness and complications such as an elevated red blood cell count (polycythemia), which makes the blood thick. Symptoms are usually precipitated by exercise and include weakness and even seizures.
There are a number of reasons for heart murmurs in puppies. These conditions require different management and include:
There are also many causes of stunted growth and of shortness of breath. Your veterinarian should investigate these symptoms.
Veterinary care should include diagnostic tests and subsequent treatment recommendations.
Diagnosis In-depth of Patent Ductus Arteriosus (PDA) in Dogs
Diagnostic tests are needed to recognize PDA and exclude other diseases. A definitive diagnosis may require additional tests including chest X-rays, electrocardiogram and ultrasound examination of the heart (echocardiography or cardiac echo). It is important to exclude other congenital heart defects. Tests may include:
Treatment In-depth of Patent Ductus Arteriosus (PDA) in Dogs
Treatments for PDA may include one or more of the following:
One should NOT delay surgery waiting for symptoms to develop. This is a common mistake (thinking: “I’ll have this fixed once we see some problems with our dog”). Anesthetic and surgical risks become greater as the heart fails and the heart muscle or lung arteries can become irreversibly damaged.
Follow-up Care of Dogs with Patent Ductus Arteriosus (PDA)
Optimal treatment for your dog requires a combination of home and professional veterinary care. Follow-up can be critical. Administer prescribed medications as directed and be certain to contact your veterinarian if you are experiencing problems treating your dog.
Following successful PDA closure, the initial follow up is about 10 to 14 days later. In uncomplicated cases, no further follow-up is required. Referral to a veterinary cardiologist can be helpful in hard to diagnose cases or when there are questions about alternative treatment options.
If heart failure has occurred, follow-up care is critical.