Feline megaesophagus associated with persistence of the right aortic arch

ABSTRACT Vascular ring anomalies are conditions that can be diagnosed in cats, although their frequency is lower than that in dogs. The fourth aortic arch is a condition characterized by the presence of a vascular ring that obstructs the physiological passage of food. The main complication is megaesophagus, with regurgitation often reported. The aim of this report is to describe the case of a cat with acquired megaesophagus due to the persistence of the right fourth aortic arch. A young cat with a history of constant regurgitation and weight loss was brought to a veterinary clinic. The patient had previously been evaluated at another veterinary clinic, but the presence of megaesophagus was not suspected based on simple radiography. In the new evaluation, megaesophagus was confirmed by thoracic radiography with a barium contrast esophagogram, with suspicion of vascular anomaly. The animal was admitted for veterinary hospitalization for intensive care and further echocardiographic evaluation to confirm the vascular anomaly. However, the cat developed aspiration pneumonia before the echocardiographic examination could be performed, and despite clinical intervention, it deteriorated and died. In the necropsy examination, persistence of the fourth aortic arch was confirmed, as well as cranial esophageal dilation proximal to the obstruction.