The First Evidence of Intermittent Rectal Prolapse in a Wild Chimpanzee ( Pan troglodytes )

Abstract

BACKGROUND: Rectal prolapse in wild chimpanzees has been rarely reported. We document a case of rectal prolapse in a wild young male chimpanzee at Mahale Mountains National Park, Tanzania. METHODS: An affected young male in the Mahale M group was observed with photographs/video and diagnosed according to operational criteria used in human (Oxford grading system). Cause and course of the prolapse were estimated by a set of longitudinal field data. RESULTS: An intermittently self-reducing full-thickness rectal prolapse was diagnosed. Protrusion fluctuated within minutes; tenesmus and diarrhea were absent; and the mucosa remained bright red and viable, without necrosis or myiasis. Post-traumatic pelvic-floor/anal-sphincter nerve dysfunction after conspecific bite injury on the buttock was estimated as the cause. CONCLUSIONS: This is the first report of rectal prolapse in wild chimpanzees. The detailed natural course of this persistent condition without medical intervention provides information relevant to case-specific management decisions in wild apes.