Despite his genetics, body condition and herd sire desirability, a mature bull with trichomoniasis can devastate the finest breeding program. Trich is a venereal disease that causes infertility, open cows and occasional abortions in cows and heifers.
The only way to identify infected bulls is to perform preputial scraping and diagnostic testing to identify the presence of the organism in the preputial folds.”
Source: The Beef Site, May 20, 2024. Link. There are no clinical signs of infection. Infected bulls do not show systemic disease, swelling, drainage or any other sign that would lead a producer to suspect infection. Bulls carry the protozoa in their prepuce and transmit it to cows through breeding.
Also see: Search for bull testing, AHD Archives. Link.