Feline aortic arch persistence: case report

Abstract

Megaesophagus is the term that refers to esophageal dilation and hypomotility, resulting from congenital, acquired or idiopathic disorder. And its occurrence in cats is considered rare when compared to dogs, with Siamese cats and their crossbreeds being the most affected. When found in cats, there are usually abnormalities of the vascular ring, foreign bodies or pyloric spasm. The most common type of vascular ring anomaly is the persistence of the right aortic arch, which corresponds to approximately 95% of patients diagnosed with the malformation. Other types of vascular ring anomalies that may be more rarely encountered include double aortic arch, left aortic arch, persistent left and right subclavian arteries, and persistent right ductus arteriosus. Persistence of the right aortic arch occurs when the right embryonic aortic arch, rather than the left one, becomes the functional aorta. When this happens, the esophagus is constricted into a vascular ring composed of the aortic arch on the right, the pulmonary artery and the base of the heart ventrally, and the ligamentum arteriosus dorsally and to the left. The esophagus is compressed by this vascular ring and begins to dilate cranially as food accumulates. Clinical signs are regurgitation, progressive weight loss, hyperxia, depraved appetite, discomfort and apathy after meals, dehydration and weakness. Respiratory signs may be present and associated with aspiration pneumonia secondary to the megaesophagus. The diagnosis is made by clinical signs, together with a simple and contrasted radiographic examination of the cervicothoracic region, where it is possible to view the dilated esophagus. There is no cure for this disease, and conservative treatment based on the patient's food management is recommended. Protocols with nasogastric and gastric catheterization can help the animal's nutrition for a while and facilitate the administration of medications. When complications secondary to the megaesophagus are present, the necessary supportive therapy must be implemented, as well as primary causes of the acquired megaesophagus must be treated when possible. All animals with megaesophagus are at risk of death due to aspiration pneumonia. When the underlying cause can be treated, megaesophagus involution or attenuation can occur. The prognosis is variable, depending on the response of each animal to the treatment instituted. The present article reports a case of congenital feline megaesophagus, seen at a Veterinary School Hospital in the interior of the State of São Paulo, which presented regurgitation as the main clinical sign and died of aspiration pneumonia.