Bacteriological and serological studies on Pasteurella multocida infection in rabbits.

Bacteriological and serological examinations were made on Pasteurella multocida infection in two rabbit-breeding colonies. The organism was localized in the paranasal sinuses of 53 of 54 infected rabbits, excreting to the external nares of 49 rabbits. It was also isolated from the trachea and middle and inner ear of half of the infected animals and occasionally from the conjunctiva, lung and heart. The infection rate of the organism was very low (4.3%) in sucklings younger than a month old, but increased with advancing age, reaching nearly 100% in adults more than five months of age. A rapid increase of the infection rate was observed at two to three months of age. Serum antibody against somatic antigen of P. multocida was demonstrated in infected rabbits by use of the tube agglutination test, showing a close correlation with isolation of the organism in adults. Sucklings younger than one month of age from infected dams were significantly resistant to experimental nasal infection of P. multocida.