CANINE AND FELINE MEGAESOPHAGUS

Megaesophagus is rare in cats and occurs as a congenital or secondary acquired disorder. In dogs, megaesophagus can occur as a congenital di sorder, as a secondary acquired disorder, or as an adult-onset idiopat hic disease. This article reviews the anatomy, pathogenesis, causes, c linical signs, diagnosis, and management of megaesophagus. Pathogenesi s includes experimental evidence that evaluates the neural pathway of affected patients. The many disease that can cause megaesophagus are d elineated. Discussion focuses on the most common causes-myasthenia gra vis, hypoadrenocorticism and possibly hypothyroidism, and the obstruct ive lesions of the esophagus (vascular ring anomalies, tumors, granulo mas, strictures, and foreign bodies). The most common clinical sign as sociated with megaesophagus is regurgitation. Traditional as well as n ewer techniques (i.e., manometry and nuclear scintigraphy) for evaluat ing esophageal motility are presented. Definitive diagnosis requires i dentification of a dilated esophagus on survey thoracic radiographs or a barium esophagogram. Medical management, including alternative feed ing methods and the role of prokinetic drugs, is discussed.