Persistent Right Aortic Arch (Vascular Ring Anomaly) in Dogs and Cats
Persistent right aortic arch is a congenital abnormality of the blood vessels of the heart that can affect esophageal function in some dogs and less commonly, in cats. Basically, an embryonic branch of the aorta fails to regress and is wrapped around the esophagus when a puppy or kitten is born. This puts pressure on the tube, preventing the passage of food in the esophagus when the pet eats, causing regurgitation. Surgery can correct the problem, and follow-up care can usually reverse the esophageal effects, especially if done early in a pet’s life.
The vascular condition known as persistent right aortic arch is also called vascular ring anomaly or vascular compression of the esophagus. It’s a condition that results from the abnormal development of the artery that arises directly from the heart, the aorta.
In the uterus, the fetus has right and left aortic arches, which rise up from the heart, then curve down to supply blood to the abdomen and beyond. During normal development, the left aortic arch remains as the main artery, while the right aortic arch regresses. If, however, the right aortic arch persists instead of, or in addition to, the left aortic arch, it can wrap around and constrict the esophagus. While it doesn’t cause a problem to the cardiovascular system itself (i.e., blood flows without impediment), the constriction of vital structures like the esophagus (the tube that carries food into the stomach) and occasionally the trachea (windpipe) can be devastating to the affected pup.
The consequence of this abnormal ring around the body’s feeding tube is often regurgitation due to a compressed esophagus. Aspiration pneumonia can also result when dogs inhale the food they’re meant to ingest.
Symptoms and Identification
Symptoms of a persistent right aortic arch become apparent once a pup starts to eat solid foods. Though milk will slide down nicely, bulky foods will jam up in the esophagus, leading to a stretched structure and the inability to get food down –– hence the regurgitation.
A stretched (dilated) esophagus, sometimes termed megaesophagus, is a typical result of the physical obstruction provided by a persistent right aortic arch. Stunted growth (due to lack of nutrition) and breathing problems (often the result of aspiration pneumonia secondary to regurgitation) are other common signs.
Diagnosis, usually undertaken after an animal is weaned and begins regurgitating, is accomplished through chest X-rays (radiography) that demonstrate a dilation in the esophagus from the throat to the base of the heart. In most cases, barium (a gastrointestinal contrast material for use in radiography) is used to highlight this dilation.
Compared to other breeds, the Great Dane, German Shepherd, and Irish Setter are more commonly affected.
Definitive treatment of a persistent right aortic arch is always surgical. A constricting ring is placed around the abnormal vessel to allow it to degenerate. Follow-up care is designed to allow the esophagus to return to its normal size and function. That may involve feeding small amounts of moistened (or slurried) food throughout the day. Feeding from a height to allow gravity to take food into the stomach is also commonly recommended.
Depending on the time of intervention (earliest is best), esophageal problems may persist despite surgery, more so if the esophagus has been severely distended and has suffered severe nerve damage prior to intervention.
Affected dogs, their parents and siblings should not be bred. This is the only known means of prevention at the current time.
This article has been reviewed by a Veterinarian.