Remission of histiocytic ulcerative colitis in Boxer dogs correlates with eradication of invasive intramucosal Escherichia coli.
BACKGROUND
Historically, histiocytic ulcerative (HUC) (or granulomatous) colitis of Boxer dogs was considered an idiopathic immune-mediated disease with a poor prognosis. Recent reports of dramatic responses to enrofloxacin and the discovery of invasive Escherichia coli within the colonic mucosa of affected Boxer dogs support an infectious etiology.


OBJECTIVE
Invasive E. coli is associated with colonic inflammation in Boxer dogs with HUC, and eradication of intramucosal E. coli correlates with clinical and histologic remission.


METHODS
Seven Boxer dogs with HUC.


METHODS
Prospective case series. Colonic biopsies were obtained at initial evaluation in 7 dogs, and in 5 dogs after treatment with enrofloxacin. Biopsies were evaluated by standardized histopathology, and fluorescence in situ hybridization (FISH) with probes to eubacteria and E. coli.


RESULTS
Intramucosal E. coli was present in colonic biopsies of 7/7 Boxers with HUC. Clinical response was noted in all dogs within 2 weeks of enrofloxacin (7 + or - 3.06 mg/kg q24 h, for 9.5 + or - 3.98 weeks) and was sustained in 6 dogs (median disease-free interval to date of 47 months, range 17-62). FISH was negative for E. coli in 4/5 dogs after enrofloxacin. E. coli resistant to enrofloxacin were present in the FISH-positive dog that relapsed.


CONCLUSIONS
The correlation between clinical remission and the eradication of mucosally invasive E. coli during treatment with enrofloxacin supports the causal involvement of E. coli in the development of HUC in susceptible Boxer dogs. A poor response to enrofloxacin treatment might be due to colonization with enrofloxacin-resistant E. coli.
Mansfield
C S
CS
School of Veterinary and Biomedical Sciences, Murdoch University, Murdoch, WA 6150, Australia. c.mansfield@murdoch.edu.au
James
F E
FE
Craven
M
M
Davies
D R
DR
O'Hara
A J
AJ
Nicholls
P K
PK
Dogan
B
B
MacDonough
S P
SP
Simpson
K W
KW
D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001706:Biopsy / Q000662:veterinary; D003093:Colitis, Ulcerative / Q000188:drug therapy / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D003106:Colon / Q000382:microbiology / Q000473:pathology; D004283:Dog Diseases / Q000188:drug therapy / Q000382:microbiology* / Q000473:pathology; D004285:Dogs; D000077422:Enrofloxacin; D004925:Escherichia / Q000254:growth & development*; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D005260:Female; D024841:Fluoroquinolones / Q000627:therapeutic use*; D006651:Histocytochemistry / Q000662:veterinary; D017404:In Situ Hybridization, Fluorescence / Q000662:veterinary; D007413:Intestinal Mucosa / Q000187:drug effects / Q000382:microbiology / Q000473:pathology; D008297:Male; D011446:Prospective Studies
D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; D000077422:Enrofloxacin