Vascular rings cause primarily respiratory difficulty in humans and swallowing difficulty in animals. A typical history for a vascular ring anomaly such as persistent right aortic arch is that of a young animal that begins regurgitating shortly after beginning on solid food. Barium esophagrams show varying degrees of esophageal dilation cranial to the heart. Although tracheal compression also may occur, it is not usually a clinical problem in animals that survive to an age at which they start on solid foods.

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The vascular ring anomaly causes deviation of the trachea, which can aid in diagnosis. In this tissue section from a normal newborn dog the aorta (A), ductus arteriosus (D), and pulmonary artery (P) are all on the left side of the trachea.

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In a one-day-old puppy that strangled due to PRAA the aortic arch (RAA) is on the right side of the trachea (T) and esophagus (E) whereas the ductus arteriosus (D) is on the left side. The trachea is deviated leftward and compressed between the two vascular structures. Strangulation occurred when the ductus contracted. The tracheal cartilages are deformed and overlapped, indicating that there was in utero compression as well.

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On DV or VD radiographs of a normal dog, the trachea (T) is usually straight and midline or curved slightly to the right. In dogs with PRAA the trachea curves leftward near the cranial border of the heart.

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Surgical correction of vascular ring anomalies normally involves ligating and dividing the structure (most often the ligamentum arteriosum) causing the constriction. With knowledge of the causes and relatively few possibilities for abnormalities, surgeons should be able to dissect out the vessels and identify all those in the area of the stricture. While the ability to do this is useful in an academic environment, it is not necessary in a practical sense, because any of the vessels or ligaments constricting the esophagus can be safely divided surgically, due to the collateral circulation via the vertebral arteries.

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Certain breeds have a higher incidence of PRAA.

Persistent Right Aortic Arch n=60
1320 Dogs with Congenital Heart Disease

Affected animals should not be used for breeding, because some degree of hereditary transmission has been demonstrated. This pedigree shows the outcome of 2 matings between littermate dogs with PRAA (shown here). In 2 litters they had one offspring with PRAA.

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This table shows the relative frequency of the various vascular ring anomalies, with PRAA being by far the most common.