Australian Shepherd Health & Genetics Institute

Australian Shepherd Health & Genetics Institute

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Patent Ductus Arteriosus


What is patent ductus arteriosus (PDA)?

PDA occurs when a fetal blood vessel that is supposed to go away before birth fails to do so.  It is one of the most common congenital birth defects in dogs.  PDA interferes with proper circulation of the blood.  When it remains (is patent), some of the blood continues to bypass the lungs and therefore does not get properly oxygenated.  Severity of disease varies depending how much blood is  not going through the lungs.  Lack of oxygen in the blood triggers the heart to work harder, with the worst cases progressing to congestive  heart failure.  The movement of blood through this vessel causes a murmur.  In some cases you can feel the vibration of the murmur simply by placing our hand over the puppy’s chest.


How do I know if my Aussie puppy has PDA?

A veterinarian may be able to diagnose PDA simply by listening to the heart.  A chest x-ray, echocardiogram, or cardiac ultrasound might also be required.

What does having PDA mean for my puppy?

Young puppies will initially seem perfectly normal.  As the disease manifests you may notice coughing, difficulty breathing, lethargy, or exercise intolerance.  Some dogs with mid disease do not require treatment, though PDA will likely shorten their lifespans.  The more seriously affected  need heart surgery, done as soon as possible to minimize further damage to the heart.  In the worst cases the disease is fatal.

How common is PDA in Aussies?

Heart problems in general are rare in the breed, but PDA and another developmental blood disorder, persistent right aortic arch (PRAA), are the type that Aussies are most likely to have.  Even so, they are still rare.

Is PDA inherited?

Yes.  Inheritance is complex; both parents should be assumed to have contributed but the contribution may be unequal.

What does producing a puppy with PDA mean for my breeding program?

Littermates of affected puppies should be checked for heart murmurs.  Dogs with PDA should not be bred.  Do not breed the parents together again, nor should you breed them or healthy full or half siblings of the affected dog close on the pedigree that produced PDA or to any dog that has a family history of PDA or persistent right aortic arch (PRAA) as both have sometimes been reported in the same family indicating there may be a genetic connection between the two.