Evaluation of procedures for the diagnosis of Brucella ovis infection in rams.

Procedures for the diagnosis of Br. ovis infection in rams were evaluated by examining 10 rams artificially infected by preputial inoculation. Observations were undertaken at weekly intervals for 1 year to follow changes in clinical, bacteriological and serological findings. Clinical lesions were detected in 1 ram 3 weeks after inoculation and in all rams by 8 weeks; lesions were undetectable in 3 rams at the completion of the trial. The presence of inflammatory cells in semen samples was the earliest indication of infection being demonstrated in 2 rams at 2 weeks and in all rams by 8 weeks; subsequently 86% of samples were positive. Br. ovis was detected in semen smears from 3 rams at 4 weeks but only one in all rams (at 27 weeks); overall 52% of semen smears were positive from 4 weeks onwards. Br. ovis was cultured from semen of 5 rams after 4 weeks and from all rams at 5 weeks; therafter 97% of samples were positive. All rams developed significant titres to the CFT between 2 and 9 weeks; therafter the CFT was a reliable indication of infection in 6 rams, highly suggestive in 3 and unreliable in one. By 8-10 weeks all rams developed significant titres to the IHA which were then maintained in all rams for the remainder of the trial.