Narrowing of the pharynx - Persistent right aortic arch

A persistent right aortic arch can lead to death of the puppies. This congenital anomaly was first diagnosed in German Pinschers in Hannover. Several German Pinscher puppies have already died from it. Therefore, a research project of the Pinscher-Schnauzer-Klub 1895 e.V. and the Institute for Animal Breeding and Genetics at the University of Veterinary Medicine Hanover Foundation is to clarify the causes for the occurrence of the persistent right aortic arch in the German Pinscher.

Persistent Right Aortic Arch (PRAA) is a congenital anomaly of the cardiac vessels. Persistent right aortic arch is found in 95% of cases of vascular ring anomalies. This anomaly has recently been observed in several German Pinscher puppies (Figs. 1 and 2). Initially, no outward signs of this anomaly are seen in the newborn pups. With the ingestion of mushy or solid food, the first clinical signs appear very abruptly. The puppies regurgitate the ingested food because, as a result of the narrowing of the esophagus above the base of the heart, further passage of the food is no longer possible or only possible to a limited extent. The cause of the narrowing of the esophagus in the German Pinscher is a persistent right aortic arch and an abnormal course of the subclavian artery. In this congenital anomaly of the cardiac vessels, the esophagus and trachea are enclosed in a ring formation by the persistent right aortic arch, the right dorsal aortic root, the ligamentum arteriosum (connecting ligament between the descending aorta and the pulmonary artery), the base of the heart, and additionally by the subclavian sinistral artery. As a result of this ring formation, the esophagus becomes so constricted that only liquid food can reach the stomach, and food of mushy or solid consistency is largely regurgitated. However, because some of the ingested food remains in the esophagus before the constriction, there is increasing dilatation of the esophagus in the precardiac region. Affected puppies are retarded in growth, become emaciated, but often show great appetite. Aspiration pneumonia may occur as a complication of pharyngeal narrowing due to persistent right aortic arch. Radiographs with oral contrast show the dilated esophagus with a marked constriction over the base of the heart. Observations in the German Pinscher showed that the esophagus dilates before the ingestion of mushy or solid food and, therefore, a diagnosis could be made from contrast radiographs before the onset of initial clinical symptoms. Individual variation is possible in the extent of constriction of the esophagus by a persistent right aortic arch. Thus, some of the affected pups were unable to ingest pulpy food, whereas other pups were still able to ingest pulpy food and regurgitated solid food first. Surgical intervention is required to remove the narrowing of the esophagus. Postoperatively, animals must be given thin mushy food while standing. The earlier the diagnosis and surgical intervention are made after the onset of clinical signs, the better the prospects for complete healing of the pharyngeal stenosis and the absence of postcardiac dilatation of the pharynx after surgery.
The Pinscher-Schnauzer-Klub 1895 e.V. and the Institute for Animal Breeding and Genetics at the University of Veterinary Medicine Hanover Foundation are conducting a joint research project for the genetic elucidation of the PRAA. For this reason, puppies affected by PRAA and their littermates should be recorded as completely as possible. Should you diagnose cases of PRAA in German Pinschers in your veterinary practice, we would be very grateful for an immediate report (phone, email, fax). It is very important for the project to get as many samples as possible of the animals affected by PRAA. From affected animals, their parents and littermates we need one EDTA blood sample each. A leaflet in German and English language is available on our homepage. If the puppy affected by PRAA is already dead, we would be very grateful if the animal owner would leave us a tissue sample (muscle sample) or the puppy as a whole for research. If a puppy is to be euthanized because of PRAA, then we ask for muscle biopsy samples, which must be preserved in a special medium (RNAlater) and taken immediately after euthanasia (within the first 15 min). We will be happy to send you this preservation fluid (RNAlater).

PRAA
German Pinscher with a persistent right aortic arch. Visualization of precardiac esophageal dilatation with radiographic contrast.
PRAA
Visualization of the vascular ring in a German Pinscher with a persistent right aortic arch.