The pathogenesis of Tritrichomonas foetus infection in the bull.
The distribution of T. foetus in the genital tract of 15 naturally infected and 9 experimentally infected bulls was assessed by cultural methods. In all animals T. foetus was present in all regions of the penis and prepuce sampled; in four naturally infected bulls it was also cultured from the anterior urethral orifice. T. foetus was confined to the preputial cavity and was not cultured from epididymidis, ampulla, seminal vesicles, pelvic urethra or testicle. Macroscopic and microscopic examination of the genital tract of the 24 infected bulls did not reveal any lesions in which T. foetus could be identified. The organism was not cultured from any of a total of 57 semen samples collected from 12 experimentally infected bulls. Results indicate that the distribution of T. foetus in the genital tract of bulls is limited to the penis and prepuce, and is localized in the preputial secretions and does not invade the epithelium of the penis or prepuce.