RESUMO
AIM: To investigate and assess the susceptibility, lesions and route of dissemination in the accessory sex organs of young rams experimentally infected with Actinobacillus seminis. METHODS: The accessory sex organs were obtained from 64 young rams. The test rams (n=52) were infected by instillation, drenching or injection of 2.3 x 10(9) cells/ml A. seminis organisms via nine different routes: intra-epididymal (1 ml), I/V (3 ml), intra-urethral (3 ml), intra-preputial (3 ml), ductus deferens (1 ml), I/M (3 ml), oral (10 ml), intranasal (3 ml), and intra-conjunctival (3 drops). All test rams were necropsied 1-44 days post-inoculation (p.i.). Control rams (n=12) were necropsied at 1-46 days p.i. Accessory sex organs were cultured for A. seminis, and thin tissue sections were collected and examined for histopathological changes. RESULTS: Vesicular adenitis was the most frequent lesion (21/52; 40%), followed by ampullitis, deferentitis, urethritis and bulbo-urethral adenitis (20/52 (38%), 16/52 (31%), 12/52 (23%), and 8/52 (15%), respectively). The prostate and prepuce were the least affected, and lesions occurred equally at 4% (2/52). Actinobacillus seminis was isolated from the accessory sex organs of 10 (19%) rams: from the vesicular glands (n=6), ductus deferens (n=3), ampullae (n=1), and prepuce (n=3). No lesions were seen in rams inoculated via the nasal and conjunctival routes. The pattern of involvement of both ascending and descending A. seminis infection of the genital tract is discussed. CONCLUSIONS: Involvement of the accessory sex organ of rams following all but the intranasal and intra-conjunctival routes of the nine routes of experimental inoculation tested helped to clarify the epidemiology, pathogenesis, and pathology of ovine genital actinobacillosis.