Pathogenicity of Pasteurella multocida A:3 in Flemish giant and New Zealand white rabbits

Pasteurella multocida A:3 was isolated during an outbreak of pasteurellosis in Flemish Giant (FG) rabbits. Since New Zealand White (NZW) rabbits housed in the same room were not as severely affected as FG rabbits, experimental inoculation was undertaken to determine if FG rabbits were more susceptible than NZW rabbits to pasteurellosis induced by this isolate. Rabbits of each breed were inoculated with P. multocida A:3 and observed for 3 weeks. Four of 5 FG rabbits developed severe clinical disease on days 6, 9, 12 and 14 after inoculation; whereas, the one affected NZW rabbit became ill 14 days after inoculation. All rabbits with clinical disease developed fibrinosuppurative pleuritis, pyothorax and pneumonia which was more severe in FG than NZW rabbits. At necropsy, P. multocida A:3 was isolated from multiple sites of the diseased rabbits. No significant difference (P = 0.099) in the prevalence of lesions between the two breeds was found; however, the score of pneumonia and pleuritis was 3 times greater in FG rabbits than NZW rabbits.