Patent Ductus Arteriosus and Your Dog

While not well-known amongst the average dog owner, Patent ductus arteriosus (otherwise known as PDA), is the number one cause of congenital heart failure in dogs. Roughly 1 out of every 150 puppies are affected with this condition, and many don't even show symptoms of having it until it's too late.

What is PDA?

Patent ductus arteriosus is a congenital disorder of the heart, meaning that the condition is present at birth. Prior to birth, all puppies have a ductus arteriosus - a blood vessel which connects the two major arteries of the body (the aorta and pulmonary arteries). While this blood vessel is normal in all puppies, it should close within 7-10 days after they are born. In puppies that suffer with PDA, this blood vessel fails to close, allowing an excess of blood to be pumped to the lungs.

Sadly, there are usually no obvious symptoms to look for when trying to diagnose PDA. While puppies that suffer from this condition tend to be smaller and don't grow as quickly as their littermates, many uninformed buyers tend to gravitate towards the smaller puppies in the litter, often making them more marketable than their peers. These people don't realize they purchased a sick puppy until it's diagnosed by a veterinarian or, worse, when the puppy's heart fails. Some people even think that their puppy is perfectly fine, despite the diagnosis, because he runs and plays like any other puppy. The figures speak for themselves though - more than 60% of dogs that are diagnosed, but left untreated, die within a year of their diagnosis.

Who is at Risk?

Any dog can be born with PDA, regardless of breed, though this condition is more common in females. Some breeds that appear to be more commonly affected include the miniature and toy poodle, Bichon frise, Collie, Yorkshire terrier, Chihuahua, Irish setter, German shepherd, Cocker spaniel and the English Springer spaniel. Breeds that seem to have the greatest risk of developing PDA are the Maltese, Pomeranian, Kerry blue terrier, and the Shetland sheepdog or Sheltie.

How PDA is Diagnosed

In most cases, there are no outward symptoms of patent ductus arteriosus unless the dog has suffered congestive heart failure at some point, causing a buildup of fluid in the lungs. The way that PDA is usually diagnosed is by a veterinarian, during a routine puppy examination and vaccinations. Due to the continual blood flow through the vessel, puppies that have PDA have what is known as a machinery, or continuous, heart murmur. Most veterinarians can determine the distinctive sound of a PDA murmur, but they may call for other tests to confirm the diagnosis and rule out any other birth defects or diseases. These tests may include the following:

A chest x-ray
An electrocardiogram (EKG)
An echocardiogram (cardiac ultrasound)

Breeding and PDA

If your dog has been diagnosed with patent ductus arteriosus, it's essential NOT to breed your dog, as there is a good risk that they can pass it down to their puppies, or that the condition my crop up further down the line. Dogs that test positive for PDA should never be bred and, for the dog's own health and happiness, should be spayed or neutered.

While there is no genetic test available for this condition, responsible dog breeders should have their breeder dogs screened by Doppler echocardiography - including breeder and pet quality siblings. While this is not a 100% guarantee, it will help to reassure potential buyers that you are contentious of the condition and doing your best to ensure people get a happy, healthy puppy from you.

Treatment for Dogs With PDA

If your dog is discovered to have PDA, the only way of treating the problem is to schedule surgery, so that the blood vessel can be properly closed. On a good note, most dogs that have this surgery go on to lead normal, healthy lives (the surgery is usually more than 90% effective). In some cases, where surgery is not an option, catheters may be used to try and block off the blood vessel. Your veterinarian will discuss the best methods of treatment for your particular case.

It cannot be stressed enough that a large number of dogs that are diagnosed as having PDA, that do not get the operation, usually die within a year of the diagnosis. If your dog is diagnosed with patent ductus arteriosus, it's essential that you get him the proper treatment - it's the only way to prevent losing your best friend.　

Sources:

http://www.addl.purdue.edu - Information on the different varieties of PDA

http://www.petplace.com - Information on different tests for PDA

Various breed clubs and organizations - Information on genetic testing