Unilateral orchitis in a bull caused by Brucella abortus biotype1

A case of Brucella orchitis in a Brahman bull is described. Positive serological titres were detected 1 month before clinical symptoms became obvious, whereas the seminal plasma only contained detectable levels of antibody after the onset of orchitis. It is concluded that serological assays on the seminal plasma alone are inadequate to detect sub-clinically infected animals, and consequently particularly bulls that are intended for use in AI centres should be subjected to a full battery of serological tests as well, before they are certified to be free of brucellosis. The pathology seen in this case was an acute, necrotic orchitis characterized by the presence of numerous granulomas containing the Brucella organisms centrally.