Abstract: Granulomatous colitis in French Bulldogs

Winner, Cases and Abstracts category
Alison Manchester, Cornell University

GRANULOMATOUS COLITIS IN FRENCH BULLDOGS IS ASSOCIATED WITH INVASIVE E. COLI AND CLINICAL RESPONSE TO FLUOROQUINOLONE ANTIBIOTICS.

A Manchester1, S Hill2, B Sabatino3, R Armentano4, B Kessler1, M Miller1, B Dogan1, SP McDonough1, KW Simpson1. 1. College of Veterinary Medicine, Cornell University, Ithaca, NY. 2. Veterinary Specialty Hospital, San Diego, CA. 3. College of Veterinary Medicine, University of Tennessee, Knoxville, TN. 4. College of Veterinary Medicine, University of Florida, Gainesville, FL.

   French bulldogs have been reported to develop a form of inflammatory bowel disease that is histopathologically similar to granulomatous colitis of Boxer dogs (GCB). GCB is associated with mucosally invasive E. coli, whose eradication correlates with clinical remission. We sought to determine the clinical features, presence or absence of intramucosal bacteria and E. coli in colonic biopsies, and response to fluoroquinolone antibiotics in French bulldogs with GC.

   Five French bulldogs (4M, 1F; median agFISH staining to identify multifocal accumulations of intramucosal E. coli in colonic biopsiese 10mo, range 5-12mo) with a histological diagnosis of GC were studied. Bacterial colonization was evaluated using eubacterial (EUB-338) and E. coli-specific FISH probes. E. coli were isolated and antimicrobial resistance was determined by broth microdilution MIC from available fresh biopsies. Response to fluoroquinolone antibiotics was determined by monitoring clinical signs.

   Dogs were presented with clinical signs of chronic hematochezia (5/5), large bowel diarrhea (3/5), and tenesmus (1/5) after failed therapeutic trials with metronidazole (5/5), various other antimicrobials (3/5), and anthelmintics. Age at onset of clinical signs was 1-7mo (median 3mo). Clinicopathologic findings and fecal analysis were unremarkable apart from mild anemia (PCV=39%) in 1/5 dogs. Abdominal ultrasound revealed patchy thickening of the colonic wall and regional lymphadenopathy in 3/4 dogs. Multiple hypoechoic foci within the colonic submucosa were observed in 1/4 dogs. Colonoscopic findings included hyperemic and irregularly thickened mucosa (5/5), overt bleeding (2/5) and mucosal ulceration (3/5). FISH revealed multifocal accumulations of intramucosal E. coli in colonic biopsies from 5/5 dogs. E. coli (2-6 strains) isolated from 2/2 dogs  were susceptible to enrofloxacin, marbofloxacin and trimithoprim sulfa. Treatment with fluoroquinolones (enrofloxacin 4/5, marbofloxacin 1/5) at 4.4-10 mg/kg (median 10 mg/kg) PO SID for 6-10 weeks was associated with clinical remission. Hematochezia resolved in 3-14 days in 5/5 dogs, and 2 dogs had gained weight within 1 month. All 5 dogs remained free of clinical signs over a 9-23 month follow up period.

   We conclude that GC in young French bulldogs is associated with the presence of invasive E. coli and closely parallels GCB. Treatment with fluoroquinolones was associated with lasting clinical remission. Documented treatment failures in GCB caution against empirical antimicrobial therapy in French bulldogs with unconfirmed GC.