Abstract :
Pasteurellosis is one of the most prevalent diseases of sheep, but the involvement of
Pasteurellae in genital pathology of rams has been described rarely. One hundred and
eighty-four rams showing palpable lesions in testes, epididymides or scrotum were submitted
to bacteriological studies, and seven mature rams found infected with bacterial
species belonging to the Pasteurella cluster (i.e., Mannheimia, Pasteurella and Bibersteinia
(M/P/B)). The M/P/B cultures obtained were pure and/or heavy, and were confirmed after
necropsy in the five M/P/B infected rams that could be slaughtered for further pathological
examinations. Pasteurella multocida infected rams exhibited fibrinous exudate and generalized
adhesions between the vaginal and the external scrotal layers. Testicular atrophy and
epididymal sperm granulomas were also evident in these rams. Microscopically, epithelial
hyperplasia with intraepithelial cysts, fibrosis and spermatic granulomas were present
in the epididymis, while testis showed sperm stasis foci, microcalcifications and fibrosis.
Mannheimia haemolytica infected rams showed severe unilateral epididymitis and testicular
atrophy, being microscopically similar to the lesions found in P. multocida infected rams.
The ram found infected with B. threalosi had severe unilateral lesions in testis, epididymis
and scrotum. Microscopically, abscesses in epididymis and testis, and severe fibrosis and
interstitial round cells infiltrates in testis were observed. Further studies should be conducted
to determine properly the role played by the Pasteurella cluster in the pathogenesis
of genital lesions in rams.
