Clinico-pathological responses in reproductive system and its associated lymph nodes of bucks challenged with Corynebacterium pseudotuberculosis and its mycolic acid extract

Abstract

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.