Etiology of infectious atrophic rhinitis of swine. 1. Relationship between the disease and bacterial flora of the nasal cavity

Abstract

Etiological studies were carried out on infectious atrophic rhinitis of swine (AR)now prevailing in Japan. A total of 654 swab samples of swine nasal discharge wereexamined to establish any relationship between the bacterial flora of the nasal cavityand the occurrence of this disease.Of these samples, 413 had been obtained from 6 swine farms in Nagasaki, Ibaraki, Saitama, Hiroshima, Kanagawa, and Yamanashi Prefectures. Other 214 samples hadbeen collected from clinically AR-suspected hogs which had been shipped from 26prefectures scattered nearly all over Japan to the Shibaura Abattoir, Tokyo, and sub-jected to the post-mortem examination for pathological change of the turbinate bones.The results obtained are summarized as follows.l. Turbinate atrophy was seen in 173 pigs (7l.3%) which had been shipped from25 prefectures all over Japan and slaughtered at the Shibaura Abattoir, Tokyo. Theseresults clearly indicate that AR has been spread among swine in Japan to a considerablylarge extent.2. Bordetella bronchiseptica was detected in relation to the clinical symptomsand turbinate atrophy. So that it was considered to be the most important pathogenicagent of infectious atrophic rhinitis of swine now prevailing in Japan.Pasteurella multocida was partially suspected as a pathogenic factor on only onepig farm. Haemophilus suis was not recognized as the primary pathogen of thisdisease. Micrococcaceae, Streptococus, Escherichia, and Mycoplasma were i nd i catedas species forming the normal bacterial flora of the nasal cavity of pigs.3. The bacterial flora of the nasal cavity of infected pigs correlated to the riseand fall of the disease. B. bronchiseptica was generally detected in the early ormiddle stage of the disease. On the other hand, Klebsiella-Enterobacter showed atendency to be isolated as a dominant species in a later stage of the disease.4. B. bronchiseptica was detected abundantly in the ethmoid turbinate evenwhen it could not be isolated in the nasal turbinate in a later stage of the disease.From this fact, it