Comparison of pathogenicity of various isolates of Bordetella bronchiseptica in young pigs.

Eight groups of 12-to 24-hour-old pigs were procured from a respiratory disease-free herd of swine and reared in isolation using a box-rearing procedure. They were inoculated intranasally at 3 days of age with different isolates of Bordetella bronchiseptica. It was found at necropsy 4 weeks post-inoculation that 4 isolates of swine origin, an isolate of rabbit origin and an isolate of cat origin caused mild to moderate turbinate atrophy in 22 of 24 pigs. An isolate of rat origin caused mild turbinate atrophy in 1 of 4 pigs and an isolate of dog origin caused no turbinate atrophy. Pneumonia was present in most of the pigs inoculated with the swine, cat and rabbit isolates. Bordetella bronchiseptica was recovered in heavy growth from the nasal and tracheal exudate collected at necropsy from pigs inoculated with the 4 isolates of swine origin and the isolate of cat origin. Fewer organisms were isolated from nasal exudate collected from pigs inoculated with the rat, dog and rabbit isolates.