E. coli associated granulomatous colitis in a French Bulldog

Abstract

A 1-year-old castrated male French bulldog, presented to a local veterinary practice several times over the course of his first year of life for chronic bloody diarrhea. No definitive diagnosis was made, and there was no response to empiric treatment which included multiple courses of metronidazole, fenbendazole, and diet modification. After nine months of treatment failure, the patient was referred to Cornell University Hospital for Animals Medicine service for further evaluation. Diffuse thickening and irregularity of the colonic mucosa was apparent at colonoscopy. Histopathology was characterized by severe chronic diffuse histiocytic, lymphoplasmacytic and neutrophilic ulcerative colitis with abundant PAS positive-stained macrophages and mucosal hyperplasia, yielding a diagnosis of Granulomatous Colitis (GC). Fluorescence in-situ hybridization (FISH) revealed invasive E. coli, and E. coli was cultured from the biopsy samples. The patient was treated with an 8 week course of enrofloxacin therapy and achieved complete remission. GC was previously considered an immune-mediated condition unique to Boxer dogs, but is now recognized as a treatable bacterial disease characterized by an intramucosal colonization of an invasive E. coli species, and has been recently documented in other breeds including the French bulldog. It is thought that affected dogs are unable to kill opportunistically invasive E.coli. Prognosis is good in patients responsive to enrofloxacin treatment, but poor to grave in those that do not respond.