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Caseous lymphadenitis (CLA) is a chronic bacterial disease that causes economic losses in small ruminant throughout the world. Corynebacterium pseudotuberculosis is the causative agent of CLA characterized by large abscesses internally/externally, abortions, weight loss, and decreased wool production in sheep and goat farming. There is paucity of information on Corynebacterium pseudotuberculosis and its immunogen mycolic acid responses in male goat during the course of CLA. As a result, this study was designed to investigate the clinical responses and pathological changes of the reproductive tract and its associated lymph nodes in male goats following inoculation with Corynebacterium pseudotuberculosis and its immunogen mycolic acids. A total of 12 healthy crossbred Boer male goats aged 16–20 months were divided into three groups, 1, 2, and 3, of four in each group. Group 1 (control group) was inoculated with 2 ml of sterile phosphate-buffered solution (PBS) via intradermal route, group 2 was inoculated with 2 ml 1 × 109 colony forming unit (cfu) of C. pseudotuberculosis intradermally and group 3 was inoculated with 2 ml of mycolic acid (1 g/ml) intradermally. The bucks were observed and assessed for changes in clinical responses daily for 60 days post challenged. At the end of the experiment, animals were slaughtered and organs of the reproductive tract and lymph nodes were harvested for histopathological investigations. In this study, all experimental bucks survived throughout the study period with some evidence of clinical manifestation such as pyrexia, weight loss, and enlargement or rupture of the lymph nodes. Microscopically, C. pseudotuberculosis and mycolic acid challenged groups showed significant cellular changes in the reproductive system and lymph nodes. Group 2 showed abscessation of the lymph nodes while group 3 did not indicate any abscess formation in the lymph nodes. For mycolic acid extract, the result revealed only mild to moderate clinic-pathological responses in bucks with no abscess formation in the lymph nodes. The result obtained added knowledge in the field of CLA research in small ruminants. In conclusion, this research revealed that C. pseudotuberculosis has a negative effect on reproductive performances of bucks and affects the clinical responses and abscess formation.

Corynebacterium pseudotuberculosis is the causative agent of caseous lymphadenitis, a debilitating chronic disease of sheep and goats. Little is known about the buck's reproductive pathophysiology with respect to inoculation with Corynebacterium pseudotuberculois and its immunogen mycolic acid extract. Therefore, this present study was designed to determine the concentration of testosterone hormone, pro-inflammatory cytokines, and semen quality of the experimental animals. A total of 12 bucks, divided into groups 1, 2, and 3 (Negative control group, Positive control group and Mycolic acid group respectively), were enrolled in this study. Following inoculation, all goats were observed for clinical responses and monitored for 60 days post-challenge and were then sacrificed. Blood samples were collected via the jugular once before inoculation and on a weekly basis post-challenge. Semen samples were collected 2 weeks post-challenge and prior to the sacrifice of the experimental animals. During the post inoculation period of 60 days, the concentration of testosterone hormone for group 2 was increased significantly (p 0.05) in weeks 5, 6, and 9 but decreased in weeks 2 and 7 post inoculation. In group 3, the mean concentration of testosterone was increased significantly (p 0.05) in weeks 5, 6, 7, and 9 post inoculation but decreased in week 2. The concentration of interleukin 6 (IL 6) in treated group 2 did not show any significant difference (p 0.05) but increased significantly (p 0.05) in week 2 post inoculation in group 3. For concentration of interleukin 1β (IL1β) in both treated groups 2 and 3 showed significant difference (p 0.05) in weeks 2 and 3 post inoculation. The tumor necrosis factor-alpha (TNF-α) concentration in both treated groups 2 and 3 did not show any significant difference (p 0.05) as compared to group 1. The concentration of interferon-γ (IFNγ) significantly increased (p 0.05) for group 2 for weeks 2, 3, 4, and 5 where else for group 3 was not in significant difference (p 0.05) compared to group 1. Both group 2 and group 3 showed a reduction in semen qualities as compared to group 1, but the severity was more intense in group 2 if compared to group 3. In conclusion, therefore, the present study concluded that the mycolic acid group revealed significant responses of testosterone hormone concentration, semen quality, and its related pro-inflammatory cytokines in bucks following infection but the severity lesser compared to Corynebacterium pseudotuberculosis group.