Patent ductus arteriosus (PDA) is a heart defect that some dogs have from birth. It can lead to heart failure, but if it is diagnosed and corrected surgically before this develops, the prognosis can be good. Often, the condition will be diagnosed after a heart murmur is detected on a routine puppy vet check.

What does "patent ductus arteriosus" mean?

The normal structure and function of the dog's heart is shown in the following animation. There are two big arteries that lead out of the heart. The one that comes from the right side of the heart, the pulmonary artery, takes blood to the lungs to pick up oxygen. When this blood returns to the left side of the heart, it is pumped around the body via the main artery called the aorta.

Animation of the normal heart anatomy and circulation:

The ductus arteriosus is a little channel that links the aorta to the pulmonary artery. In the developing foetus, when the lungs are not working yet, this channel is very useful to pert blood away from the lungs to the rest of the body. However, once the lungs begin to function at birth, this duct should close.

Patent ductus arteriosus is when the duct does not close properly. When the duct remains open, some of the blood is forced from the aorta into the pulmonary artery every time the heart beats. This means that more blood travels to the lungs than normal, and the extra blood returning from the lungs can overload the left-hand side of the heart. If the condition is not diagnosed or treated, this stress on the heart can result in heart failure.

What are the signs of a patent ductus arteriosus?

The severity of the signs and how early in life they develop depends on how big the heart defect is. Often, the first clue that your dog has a patent ductus arteriosus will be when the vet detects a heart murmur at a routine puppy check.

The sound of the murmur associated with a patent ductus arteriosus is quite characteristic, but there are other potential reasons for heart murmurs and your vet is likely to suggest some investigation to definitively diagnose the cause. This investigation will probably include an ultrasound scan of the heart, and potentially other tests such as X-rays or an ECG.

If the disease is not diagnosed and treated early in life, dogs may develop symptoms that indicate the heart is struggling. These include difficulties exercising, shortness of breath and stunted growth. If your pet shows any of these signs, it is worth getting them checked out by your vet.

Are some breeds more likely to develop disease?

Patent ductus arteriosus is more common in certain breeds of dog, including:

  • Poodle
  • Yorkshire Terrier
  • Maltese Terrier
  • German Shepherd Dog
  • Newfoundland
  • Chihuahua

The condition is also more often seen in female dogs than males.

Is there a treatment for patent ductus arteriosus?

Patent ductus arteriosus can be treated surgically, and your vet will help you decide whether to opt for this with your pet. There are different procedures that can be used: either traditional open-chest surgery or a less invasive procedure in which a device to block off the duct is introduced through a catheter. Your vet will be able to discuss the different options with you and advise what would be best for your dog.

If surgery is carried out before heart failure develops, the prognosis is very good and the dog is likely to live a normal life after surgery. If heart failure has already developed, the prognosis is less favourable and it is likely that long-term medication will be needed.

As the condition has a genetic basis, breeding from affected dogs is advised against.

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