Todayโs path rounds are on ๐ฉ๐๐ซ๐ฌ๐ข๐ฌ๐ญ๐๐ง๐ญ ๐ซ๐ข๐ ๐ก๐ญ ๐๐จ๐ซ๐ญ๐ข๐ ๐๐ซ๐๐ก๐๐ฌ!
๐๐ก๐๐ญ ๐ข๐ฌ ๐ข๐ญ?
๐๐๐ซ๐ฌ๐ข๐ฌ๐ญ๐๐ง๐ญ ๐ซ๐ข๐ ๐ก๐ญ ๐๐จ๐ซ๐ญ๐ข๐ ๐๐ซ๐๐ก is a developmental condition where the ๐๐จ๐ซ๐ญ๐, the major vessel leaving the heart to deliver blood to the body, develops from the wrong site in the embryo.
๐๐ก๐จ ๐ ๐๐ญ๐ฌ ๐ข๐ญ?
This condition most commonly seen in dogs, although technically any species could get it.
๐๐ก๐๐ญ ๐๐๐ฎ๐ฌ๐๐ฌ ๐ข๐ญ?
Normally, the aorta develops from the ๐ฅ๐๐๐ญ ๐๐จ๐ฎ๐ซ๐ญ๐ก ๐๐จ๐ซ๐ญ๐ข๐ ๐๐ซ๐๐ก, which allows it to run alongside the ๐ฉ๐ฎ๐ฅ๐ฆ๐จ๐ง๐๐ซ๐ฒ ๐๐ซ๐ญ๐๐ซ๐ฒ, the vessel going from the heart to the lungs. Under these circumstances, the ๐๐ฎ๐๐ญ๐ฎ๐ฌ ๐๐ซ๐ญ๐๐ซ๐ข๐จ๐ฌ๐ฎ๐ฌ, a vessel between the pulmonary artery and the aorta in fetuses, is able to connect the two large vessels without much issue. After the animal is born, the ductus arteriosus is no longer needed, so it becomes a band of scar tissue, still connecting the two major vessels.
In persistent right aortic arch, the aorta develops from the ๐ซ๐ข๐ ๐ก๐ญ ๐๐จ๐ฎ๐ซ๐ญ๐ก ๐๐จ๐ซ๐ญ๐ข๐ ๐๐ซ๐๐ก instead. This ultimately means it ends up wrapping around the developing esophagus, before continuing down to follow the pulmonary artery. However, now the ductus arteriosus extends over top of the esophagus. Once the vessel becomes scar tissue, it ends up compressing the esophagus against the trachea. Uh oh!
๐๐ก๐ฒ ๐ข๐ฌ ๐ญ๐ก๐ข๐ฌ ๐ ๐ฉ๐ซ๐จ๐๐ฅ๐๐ฆ?
Because there is a band of scar tissue pushing down on the esophagus, it ends up blocking the normal passage of food into the stomach. Often, these young animals appear totally normal at birth, and continue to seem normal because their motherโs milk is easily able to bypass the area of compression. However, once the animal begins eating solid food, their meals have nowhere to go! This leads to regurgitation of any solid food provided, and can cause ๐ฆ๐๐ ๐๐๐ฌ๐จ๐ฉ๐ก๐๐ ๐ฎ๐ฌ (dilation of the esophagus). Sometimes, these animals can get ๐๐ฌ๐ฉ๐ข๐ซ๐๐ญ๐ข๐จ๐ง ๐ฉ๐ง๐๐ฎ๐ฆ๐จ๐ง๐ข๐ from their regurgitation, because food particles may accidentally end up going down the trachea.
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐๐ข๐๐ ๐ง๐จ๐ฌ๐๐?
Usually the clinical sign of a young puppy suddenly regurgitating once it starts eating solid food is a major indicator of a PRAA. To confirm the diagnosis, the veterinarian can do a ๐๐๐ซ๐ข๐ฎ๐ฆ ๐ฌ๐ญ๐ฎ๐๐ฒ, where they give the dog food containing barium, which shows up on X-ray. After the dog has eaten, the X-ray will show wherever the food has been, and indicate the relative size of the esophagus.
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐ญ๐ซ๐๐๐ญ๐๐?
Fortunately, this condition is treatable! Because the ductus arteriosus is no longer needed in adult animals, a surgeon can go into the thorax and simply cut the scar tissue band, and allow normal esophagus function. Cool!
๐๐ก๐จ๐ญ๐จ๐ฌ
1) A diagram to help visualize what is happening in PRAA! I hope you enjoy my beautiful art 
2) An X-ray after a barium meal. The big white blob is the enlarged esophagus, packed with food. You can see some fine wisps of food carrying on to the stomach, but certainly not enough to keep an animal healthy!
3-6) Examples of PRAA at necropsy, showing how the scar tissue compresses the esophagus.
๐๐จ๐ฎ๐ซ๐๐๐ฌ
Maxie, G. Jubb, Kennedy and Palmerโs Pathology of Domestic Animals, Volume 3. Sixth Edition.
Photo 6 ยฉ University of Calgary Diagnostic Services Unit.
Photos 2-5 ยฉ Noahโs Arkive contributors Ohio State Vet Biosciences, Synder, Nation, Wheaton licensed under CC BY-SA 4.0.
