Abstract: The resistance of field-raised swine to dysentery infection is increased by a sequence of parenteral and oral administrations. First there is parenterally administered to the swine an injectable cell concentrate containing a virulent isolate of killed cells of Treponema hyodysenteriae, and not less than five days after the animals have received the first of the parenteral injections, a series of oral administrations of enteric-coated pellets is started, the pellets containing concentrated killed cells of a virulent isolate of T. hyodysenteriae. The oral administrations are given at least once every 24 hours for a period of at least five days.

Abstract: A combination vaccine for increasing the resistance of swine to dysentery infection comprises killed cells of a virulent isolate of Treponema hyodysenteriae in combination with concentrated killed cells of Bacteroides vulgatus, or Fusobacterium necrophorum, or mixtures thereof. This combination vaccine can be adapted for either oral or parenteral administration. For parenteral administration preferably only Bacteroides vulgatus is used in combination with Treponema hyodysenteriae. The oral vaccine is enteric-coated.