Intestinal Adenocarcinoma with Cloacal Prolapse and Reduction in a Northern Leopard Frog (Lithobates pipiens)

Abstract

Over a 3-month period, a 6-yr-old, wild-caught, northern leopard frog (Lithobates pipiens) presented for reoccurring cloacal prolapse, despite surgical correction. Two contrast radiographic series performed approximately 6 wk apart showed intestinal obstruction and gastrointestinal dysmotility, while exploratory coeliotomy revealed a minor intestinal intussusception. Approximately 6 months after the fourth and final prolapse had resolved, the animal died of natural causes. Necropsy examination exposed a large, ill-defined thickening of the distal intestinal wall, with proximal intestinal dilation. Histopathology revealed a mass composed of polygonal cells, with occasional intracytoplasmic mucin arranged in sheets, and poorly formed acini, consistent with an intestinal adenocarcinoma. A presumptive metastatic lesion was identified in the kidney (microscopically). Herpesvirus-specific consensus polymerase chain reaction (PCR) and nested PCR assays performed on the formalin-fixed, paraffin-embedded intestinal and kidney masses for ranid herpesvirus 1 were negative. Few reports of intestinal adenocarcinoma in amphibians exist in the literature. To the authors' knowledge, this represents the first report of spontaneous intestinal adenocarcinoma in a northern leopard frog.