J. H. Dufty

Early pathogenesis and pathology of Tritrichomonas foetus infection in virgin heifers

Abstract The mating of a bull infected with Tritrichomonas foetus var. brisbane to 20 susceptible nulliparous cows resulted in 19 of the animals becoming infected after a single service. After T. foetus infection was confirmed, 2 cows were killed at approximately 2 week intervals in the order of mating to the bull. All cows were killed within 100 days of the commencement of mating. Eleven of the 18 cows that were killed 28 days or more after mating were pregnant. T. foetus was cultured from several areas of the genital tract in the 8 cows killed from 15 to 50 days after mating. The organism was found in the vagina and cervix of all cows, in the uterus in 6 and in the oviducts of 4. No macroscopic or microscopic lesions attributable to T. foetus infection were seen in any of these animals. Of the 12 cows killed from 60 to 100 days after mating 7 had acute or chronic microscopic lesions in many areas of the genital tract. Abortion was pending in 2 that were mated at 60 and 95 days previously, and a third cow had a pyometra. The remaining 5 cows had no macroscopic or microscopic lesions and T. foetus was cultured from the cervix and vagina of 1 animal only. T. foetus appeared to be confined to the surface secretions in the genital tract.

Vaccination of heifers with Vibrio fetus (intestinal type) against infection with Vibrio fetus (genital type)

Abstract Two subcutaneous injections of a vaccine prepared from Vibrio fetus (intestinal type) protected 11 out of 12 Hereford heifers against infection of the reproductive tract with Vibrio fetus (genital type). Vaccination resulted in a substantial and sustained serological response and the occurrence of detectable antibody in the vaginal mucus of the heifers. Although the agglutinating antibody against Vibrio fetus (intestinal type) in the vaginal mucus of vaccinated heifers produced crossreactions against V. fetus (genital type), titres were almost always less than against V. fetus (intestinal type).