Infection with and antibody response to Pasteurella multocida and Bordetella bronchiseptica in immature rabbits.

At 2, 4, 6, 8 and 10 weeks of age rabbits were cultured for Pasteurella multocida and Bordetella bronchiseptica from the paranasal sinuses, trachea, middle ears, lungs and liver. Sera were tested for antibodies (IgG) against P. multocida and B. bronchiseptica. Pasteurella multocida was isolated from all ages of rabbits, and B. bronchiseptica was isolated from rabbits 4 to 10 weeks old. The sinuses were colonized most often, followed by the trachea, middle ears and lungs. No bacteria were isolated from the liver. The number of rabbits with antibodies against both bacteria decreased between 2 and 6 weeks of age, indicating a fall in maternal antibodies, and increased between 6 and 8 weeks of age, suggesting an active humoral response.