The production of pneumonia with or without pleurisy in gnotobiotic piglets with pure cultures of strain TR 32 of Mycoplasma hyorhinis

Nine gnotobiotic piglets, when 8-9 days old, were exposed to an aerosol of strain TR32 of Mycoplasma hyorhinis and killed at intervals from 14 to 37 days after infection. The aerosol of M. hyorhinis caused bronchopneumonia in 1 pig, pleurisy alone in 2 pigs, pleuropneumonia in 2 pigs and no lung changes in 4 pigs. M. hyorhinis was re-isolated from the lungs of all infected pigs, irrespective of the presence or absence of lesions, though it was only isolated from the serosa and joints when lesions were present. Four control pigs exposed to aerosols of mycoplasma medium had no lesions.