Esophagitis denotes a localized or diffuse inflammation of the esophageal mucosa. It is generally thought to result from a caustic or chemical (ie, gastric acid, bile acids) injury. In humans, the most frequent mechanism causing esophagitis is gastroesophageal reflux (GER) leading to GER disease (GERD). GERD is thought to result from lower esophageal sphincter (LES) incompetence. In small animal medicine, GERD secondary to a primary functional LES abnormality is poorly understood, most probably because diagnosing GERD based on a detailed questionnaire on perceived symptoms, as it is done in human medicine, is not applicable. The situation becomes even more complicated when considering that the nonerosive form of GERD (ie,absence of visible lesions on esophagoscopy and the presence of reflux-associated
symptoms) comprises the majo rity of patients in human medicine.