A study of swine dysentery by immunofluorescence and histology.

Twenty-six specific-pathogen-free pigs were fed pure cultures of Treponema hyodysenteriae. Five untreated pigs were controls. Distribution of this large spirochete in pigs with swine dysentery was shown by the indirect fluorescent antibody technique. Findings by this method were compared with those from dark-field examination of colonic mucosal scrapings and from tissue sections. The cultures caused mucohemorrhagic colitis which by 10 days after inoculation was indistinguishable from the colitis of swine dysentery. Control pigs remained normal. Pigs killed when spirochetes were first seen in the feces had normal colonic mucosa with only a few spirochetes. At the first sign of diarrhea, however, the colonic mucosa was thicker than normal and had many spirochetes. T. hyodysenteriae was confined to regions of hypertrophy and exudation of the large intestine mucosa throughout the course of disease.