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Summary
The cardiovascular disease known as persistent right aortic arch is also known as "vascular ring anomaly" and "vascular compression of the esophagus." It's a disease that's the result of an abnormal re-routing of the blood vessel in the artery that arises directly from the heart, the aorta.
Though this vessel is normal in the developing embryo, its presence in the developed animal is problematic: While it doesn't cause a problem to the cardiovascular system itself (i.e., blood flows without impediment), its existence has a way of constricting vital structures like the esophagus (the tube that carries food into the stomach) and occasionally the trachea (the windpipe).
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 (primarily affected) inhale the food they're meant to digest as it's unable to make its way down to the stomach.
Symptoms and Identification
Symptoms of a persistent right aortic arch become apparent once a pup starts to take in solid food. While 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 symptom known as regurgitation.
A stretched (dilated) esophagus, sometimes termed "megaesophagus" is a typical cause secondary to the physical obstruction provided by a persistent right aortic arch. Stunted growth (due to an inability to take in nutrients) and breathing problems (often the result of aspiration pneumonia secondary to regurgitation) are other common symptoms.
Diagnosis, usually undertaken after an animal is weaned and begins regurgitating, is accomplished through chest X-rays that demonstrate a dilation in the esophagus from the throat to the base of the heart. Sometimes barium (a gastrointestinal contrast material) is used to elucidate this dilation.
Affected Breeds
Compared to other breeds, the Great Dane, German Shepherd and Irish Setter are more commonly affected.
Treatment
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 mechanic effectiveness. That may involve feeding small amounts of moistened (or slurried) food in multiple feedings throughout the day. Feeding from a height to allow gravity to bring 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.
Veterinary Cost
The cost of diagnosis and surgical intervention varies between $2,000 and $6,000, depending on the facility and geographic location. Because a cardiologist and/or veterinary surgeon are usually involved in this uncommonly applied therapy, the price of treatment tends towards the higher end of this range.
Prevention
Affected dogs and their parents and siblings should not be bred. This is the only known means of prevention at the current time.
References
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 counseling for congenital heart defects.