Porcine colonic spirochetosis: a retrospective study of eleven cases.

This retrospective study of porcine colonic spirochetosis was done in order to characterize the clinical signs, the macroscopical and microscopical changes, and the bacteriological results of cases observed in Quebec. Necropsy records of all cases of colitis were reviewed. Eleven cases with filamentous bacteria colonizing the colonic epithelium were selected. This condition was only observed in weaned piglets, and was associated with mild persistent diarrhea and growth retardation. Macroscopic changes were generally limited to the presence of soft to liquid colonic contents. Adherence of filamentous helicoidal bacteria to the apical surface of the colonic epithelium and mild diffuse infiltration of the colonic lamina propria by mononuclear cells were the main histological findings. Weakly beta-hemolytic spirochetes were isolated in 6 cases. This condition seems to be underestimated for various reasons, and it is possible that some cases diagnosed as nonspecific colitis or superficial colitis, in fact, represent later stages of porcine colonic spirochetosis.