Idiopathic distal esophageal dilation in a southern black rhinoceros (Diceros bicornis minor)

An adult female southern black rhinoceros (Diceros bicornis minor)experienc ed intermittent periods of regurgitation while eating, suggesting an esopha geal disorder. Endoscopy for evaluation of the trachea, esophagus, and stom ach revealed a 30-mm nasopharyngeal orifice with associated recess located in the caudodorsal pharynx and a 10-cm dilated segment of the distal esopha gus that was presumably the cause of regurgitation. Dietary management of e sophageal dilation through short-term utilization of a "soft feed." program successfully eliminated the regurgitation. This is the first report of eso phageal dysfunction in a rhinoceros.