Persistent Right Aortic Arch (PRAA)


This is actually a vascular abnormality that results in constriction of the oesophagus over the base of the heart, causing a build up of food forward of the obstruction.   Signs are regurgitation of solid foods almost immediately after eating (seen from 3-4 weeks of age). These are diagnosed by their very characteristic appearance on barium X ray. In this type of abnormality, the actual musculature of the oesophagus is normal.  Praa  can be corrected surgically (usually not before 12-14 weeks of age), however as the operation is intra-thoracic, the puppy usually has to be of a reasonable size and weight before operation. The prognosis can be guarded as the puppies are often thin, undersized and there can be secondary pneumonia.  Most improve dramatically after the operation, however some can persist in having some dilatation in the 1st 1/3 of the oesophagus. Feeding of these puppies is by giving them a more liquid diet and feeding them with the food in an elevated position so as to provide a straighter passage through the chest to the stomach.


What is PRAA


Vascular ring anomaly, vascular compression of the esophagus

praa3 What is a persistent right aortic arch?
The term vascular ring anomaly describes several disorders that occur because of abnormal development of the blood vessels that arise from the aortic arch in the fetus. The most common abnormality is a persistent right aortic arch which develops instead of the left aortic arch that would normally become the permanent aorta, the main blood vessel leading from the heart.

Click to see enlarged image

These anomalies are relatively common in dogs. They do not cause cardiovascular problems; however the abnormal blood vessel forms a ring which entraps the esophagus and sometimes the trachea, causing regurgitation, unthriftiness, and often aspiration pneumonia.

How is a persistent right aortic arch inherited?
Inheritance is complex.

What breeds are affected by persistent right aortic arch?
There is an increased incidence of this disorder in the Great Dane, German Shepherd and Irish setter, relative to other breeds.

What does a persistent right aortic arch mean to your dog & you?
Signs associated with entrapment of the esophagus usually become apparent shortly after weaning, when the dog begins eating semi-solid or solid food. The partial obstruction of the esophagus causes regurgitation and, over time, dilation of the esophagus ahead of the obstructed area. Dogs with this condition are thin, may be malnourished and have ravenous appetites. They are prone to aspiration pneumonia.

These anomalies can be corrected surgically. It is important to do so before there is permanent damage to the esophagus.

How is a persistent right aortic arch diagnosed?
In a dog that begins regurgitating shortly after weaning, this condition is suspected. Chest x-rays will confirm this, in particular a contrast study with barium which will show the dilated esophagus just ahead of the obstruction, located at the base of the heart. It is important to differentiate this condition from megaesophagus, which causes similar signs and in which the esophagus is dilated throughout its length.

How is a persistent right aortic arch treated?
Treatment is surgical. The constricting ring is separated. Surgery should be performed early, before permanent damage has occurred to the lining of the esophagus due to distension.

Postoperative care involves feeding a liquid diet with gradual introduction of frequent small meals. In some dogs occasional regurgitation may persist.

Breeding advice
Affected individuals and their parents should not be used for breeding. Siblings should only be used after careful screening. If any affected offspring are born, breeding of the parents should be discontinued.


Patterson, D.F.  1996. The genetics of canine congenital heart disease.  ACVIM-Proceedings of the 14th Annual Veterinary Medical Forum: 225-226.   This reference has good information for breeders and veterinarians regarding screening and genetic counselling for congenital heart defects.

This database is funded jointly by the Animal Welfare Unit at the Atlantic Veterinary College, University of Prince Edward Island, and the Canadian Veterinary Medical Association.
Copyright © 1998 Canine Inherited Disorders Database.  All rights reserved. Revised: October 30, 2001.
reprinted with kind permission from:-
 Alice Crook, DVM,Coordinator, Sir James Dunn Animal Welfare Centre, Atlantic Veterinary College,University of Prince Edward Island, 550 University Ave.Charlottetown, PEI C1A 4P3
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Case Study
Megaesophagus Secondary to PRAA
Lilli's Story
Daisy's Story
Angel's Story
Tracheal signs of PRAA
Embryogenesis of PRAA and Related Vascular Anomalies

chloebutton  talabutton  

The above information is simply informational. It's intent is not to replace the advice of a veterinarian nor to assist you in making a diagnosis of your pet. Please consult with your own veterinarian for confirmation of any diagnosis. Your pets life may depend on it.