B. ovis is generally introduced into a flock via infected sheep or semen. For this reason, clinical examination (palpation of the scrotum) and serological screening (detection of antibodies) of potential breeding rams or rams with unknown health status prior to introduction into the flock are the most important preventive measures against the spread of the pathogen. Infections in ewes can be prevented by controlling B. ovis in rams.
The reservoir for B. ovis infections is chronically infected rams. The pathogen may persist in testes, epididymis accessory gonads, or kidneys and be shed intermittently for years.
After mating with an infected ram, the pathogen can survive in the vaginal secretions of the female sheep and be transmitted to an uninfected ram during the next mating. Females usually shed the pathogen after a few months, thus contributing only temporarily to further spread in the flock. Abortions or the birth of weak lambs due to placentitis of the infected ewe occur rather rarely. Young rams, even though they have not yet been used for mating, can become infected from infected rams through social interaction in the ram flock (sniffing urine or semen, or ranking fights with rectal copulation). Rams from flocks of unknown status should not be kept with other rams or used for breeding. Ewes recently mated by infected rams pose a potential risk of infection to healthy rams.
The majority of B. ovis infections are asymptomatic or changes (genital lesions) do not become clinically apparent until a late stage of infection. Aries become clinically conspicuous by unilateral, rarely bilateral, palpable changes of the epididymis (epididymitis). Economic loss due to alteration of breeding parameters in the flock is often only visible in intensive sheep farming.