Regeneration of toxigenic Pasteurella multocida induced severe turbinate atrophy in pigs detected by computed tomography

BACKGROUND Atrophic rhinitis is a widely prevalent infectious disease of swine caused by Bordetella bronchiseptica and Pasteurella multocida. The course of the disease is considered to be different depending on the principal aetiological agents distinguishing B. bronchiseptica induced non-progressive and toxigenic P. multocida produced progressive forms. In order to compare the pathological events of the two forms of the disease, the development of nasal lesions has longitudinally been studied in pigs infected by either B. bronchiseptica alone or B. bronchiseptica and toxigenic P. multocida together using computed tomography to visualise the nasal structures. RESULTS B. bronchiseptica infection alone caused moderately severe nasal turbinate atrophy and these lesions completely regenerated by the time of slaughter. Unexpectedly, complete regeneration of the bony structures of the nasal cavity was also observed in pigs infected by B. bronchiseptica and toxigenic P. multocida together in spite of seeing severe turbinate atrophy in most of the infected animals around the age of six weeks. CONCLUSIONS B. bronchiseptica mono-infection has been confirmed to cause only mild to moderate and transient lesions, at least in high health status pigs. Even severe turbinate atrophy induced by B. bronchiseptica and toxigenic P. multocida combined infection is able to be reorganised to their normal anatomical structure. Computed tomography has further been verified to be a useful tool to examine the pathological events of atrophic rhinitis in a longitudinal manner.