Effects of intranasal inoculation with Bordetella bronchiseptica, porcine reproductive and respiratory syndrome virus, or a combination of both organisms on subsequent infection with Pasteurella multocida in pigs

Objective—To determine effects of intranasal inoculation with porcine reproductive and respiratory syndrome virus (PRRSV) or Bordetella bronchiseptica on challenge with nontoxigenic Pasteurella multocida in pigs. Animals—Seventy 3-week-old pigs. Procedure—In experiment 1, pigs were not inoculated (n= 10) or were inoculated with PRRSV (10), P multocida (10), or PRRSV followed by challenge with P multocida (10). In experiment 2, pigs were not inoculated (n = 10) or were inoculated with B bronchiseptica (10) or PRRSV and B bronchiseptica (10); all pigs were challenged with P multocida. Five pigs from each group were necropsied 14 and 21 days after initial inoculations. Results—Pasteurella multocida was not isolated from tissue specimens of pigs challenged with P multocida alone or after inoculation with PRRSV. However, in pigs challenged after inoculation with B bronchiseptica, P multocida was isolated from specimens of the nasal cavity and tonsil of the soft palate. Number of bacteria isolated increased in ...