Clinical and Pathological Changes in Rams Experimentally Infected withActinobacillus seminisandHistophilus somni

Infectious epididymitis is considered a major cause of economic losses for the sheep industry worldwide. This study aimed to investigate clinical and pathological changes associated with experimental infections withA. seminisandH. somniin rams. Twenty rams of age 18 to 24 months were infected by intraepididymal inoculation ofA. seminis(n=10) andH. somni(n=10). Rams were weekly examined and biological samples were collected during six weeks. All rams inoculated withA. seminisand 80% inoculated withH. somnibecame infected. The recovery of bacteria was possible in semen and urine samples and tissues in both experimental groups. Clinically, there were a decrease in testicular consistency and an increase in measures of the left epididymis tails in both experimental groups. The main gross changes were observed in the reproductive tract. Microscopically, the main lesions were inflammatory changes in the genitourinary tract and testicular degeneration.A. seminisandH. somniwere able to colonize several organs of the genitourinary tract in rams, being indistinguishable by clinical exam, necropsy or histopathology. For differential diagnosis, it is important to use diagnostic techniques for direct confirmation of the etiologic agent.