Long-term effect of Bordetella bronchiseptica infection in neonatal pigs.

A total of 62 gnotobiotic pigs were inoculated with Bordetella bronchiseptica at 7 days of age. There were 25 noninoculated controls. Thirteen of the inoculated pigs were killed and 6 pigs which died were examined between 3 and 5 weeks after inoculations were done (group A). Of these 19 pigs, 16 had severe pneumonia and B bronchiseptica was isolated from the lungs of 17. The turbinates in most of the pigs appeared to have some atrophy. Four other pigs died of pneumonia after they were transferred to the floor in isolation rooms, and 9 inoculated pigs were examined at necropsy at about 112 days of age (group B). Bordetella bronchiseptica was isolated from 8 of the latter 9 pigs, and 7 of the pigs had pneumonic lesions. The turbinates all appeared normal. Thirty inoculated pigs (group C) were killed at 180 days of age. Of these, 22 had pneumonic lesions. Bordetella bronchiseptica was reisolated from the turbinates of 2 of 30 pigs, although the turbinates in all appeared normal. The noninoculated controls examined at necropsy at 3 to 5 weeks, 112 days, and 180 days of age did not have any pulmonic lesions, and their turbinates appeared normal. The inoculated pigs killed at 112 days of age gained an average of 0.25 kg/day, and the control pigs gained 0.31 kg. At 180 days of age, the inoculated pigs had gained 0.41 kg/day and the controls, 0.49 kg. Bordetella bronchiseptica infection in susceptible pigs can cause a severe pneumonia which can persist and reduce the growth rate.