This study was conducted to investigate the effects of exposure to porcine reproductive and respiratory syndrome virus, Salmonella choleraesuis, and stress on young swine. Five-week-old segregated early weaned pigs were randomly assigned to one of eight treatments consisting of all possible combinations of three factors: S. choleraesuis (SC) on day zero, porcine reproductive and respiratory syndrome virus (PRRSV) on day three, and dexamethasone (DEX) on days three to seven. DEX was used as a proxy for stress. Treatment differences were seen in performance parameters, levels and duration of SC shedding, level and distribution of SC in tissues, clinical disease, and mortality. The results of this study provided evidence to support field observations that clinical outbreaks of PRRS are the result of interactions among concurrent infections and stressors.
Iowa State University
Wills, Robert W.; Fedorka-Cray, Paula; Yoon, Kyoung-Jin; Gray, Jeffery T.; Stabel, Tom J.; and Zimmerman, Jeffrey J., "Synergism between Porcine Reproductive and Respiratory" (1997). Swine Research Report, 1996. 65.