Australian Shepherd Health & Genetics Institute

Australian Shepherd Health & Genetics Institute

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Persistent Right Aortic Arch


What is persistent right aortic arch (PRAA)?
PRAA occurs when the vessel that becomes the aorta arches to the right instead of the left, encircling the esophagus and sometimes the trachea.  Affected puppies regurgitate frequently and are at risk of aspiration pneumonia if regurgitated food is drawn into the trachea (windpipe.)  If the trachea is encircled PRAA it may to some degree inhibit the passage of air.  The constriction of the esophagus can lead to megaesophagus, in which the esophagus becomes grossly over-expanded due to the back-up of food as it works past the constriction.  This makes it even more difficult for food to pass properly into the stomach.

How do I know if my Aussie puppy has PRAA?
Once a PRAA puppy starts eating solid food it will regurgitate frequently and may choke on its food.  Regurgitated food will be undigested and may be in a tubular shape. PRAA pups are often very thin even though they have ravenous appetites.  Your vet will rule-out other possible causes of vomiting first and diagnosis will be confirmed with a chest x-ray.

What does having PRAA mean for my puppy?
PRAA can be corrected surgically; surgery must be performed as early as possible to prevent permanent damage to the esophagus.  There is a long period of post-operative care that starts with a liquid diet and requires that the puppy be held upright during and for a period after eating; when solid food is introduced the pup will have to be fed several small meals per day.

How common is PRAA in Aussies?
Heart problems in general are rare in the breed, but PRAA and another developmental heart vessel defect called patent ductus arteriosus (PDA) are the types that Aussies are most likely to have.  Even so, they are still rare.

Is PRAA inherited?
Yes, but inheritance is complex.

What does producing a puppy with PRAA mean for my breeding program?
Get any littermates checked for heart murmurs, which mayindicate PRAA.  Dogs with PRAA should not be bred.  Do not breed the parents together again, nor should you breed them or any of their healthy puppies to their near relatives or to any dog that has a family history of PRAA or PDA as ASHGI has received reports of both occur in the same families.