Diagnosing gastric ulcers in bottlenose dolphins (Tursiops sp.) using gastroscopy and cytology

Abstract

Gastric ulcers have been reported in a range of cetacean species. Bottlenose dolphins (Tursiops spp.), the most common cetacean species held in captivity, are known to experience gastric ulcers in both wild and captive environments. Documented causes of gastric ulceration include bacterial infection by Helicobacter sp., parasitic infections, high dietary histamine and foreign body ingestion. Gastric ulceration without any obvious cause might be related to stress. Currently, the most accurate way to determine the presence of gastric ulcers in captive dolphins is through direct examination of the stomach mucosa using endoscopy (gastroscopy); a procedure that requires substantial animal training and specialised medical equipment. In this study, we investigate whether cytology of the gastric fluid, collected through the less intensive method of intubation, can be used as an alternative to gastroscopy to predict the presence and severity of gastric ulcers in eight captive bottlenose dolphins at uShaka Sea World, South Africa. An ulcer grading scale was developed to quantify the severity of the dolphins' gastric ulcers observed using gastroscopy. Gastric ulcer severity was then compared with the cytological data collected from gastric fluid samples taken during the gastroscopic examinations. The cytological findings were consistent with other studies, but ulcer severity was not found to be linked to the cytological parameters measured. From these results we suggest that routine cytology of the gastric fluid is not a viable alternative to gastroscopy for diagnosing gastric ulcers in bottlenose dolphins.