RESPIRATORY-DISEASE IN CALVES PRODUCED WITH AEROSOLS OF PARA-INFLUENZA-3 VIRUS AND PASTEURELLA-HAEMOLYTICA

  • 1 January 1982
    • journal article
    • research article
    • Vol. 46  (3) , 293-301
Abstract
In 4 experiments, 22 calves were exposed to aerosols of parainfluenza-3 virus, followed by P. haemolytica at intervals of 3-13 days. The purpose of each experiment was to study viral-bacterial interactions in the respiratory tracts. Two experiments, in which the viral aerosols were diluted by the addition of air, produced sporadic temperature elevations while 2 experiments with undiluted viral aerosols produced consistent temperature elevations. Diluted viral aerosols produced lobular sized lesions in the lungs and hemagglutinating inhibition antibodies in sera; undiluted aerosols produced a synergistic effect in the form of purulent pneumonia in 10 of 14 calves when the interval between viral and bacterial aerosols was from 3 to 10 days. Histopathological changes attributable to the virus only were seen in all experiments; the histopathological changes due to mixed infection of parainfluenza-3 virus and P. haemolytic are described in detail. This is probably the 1st report of extensive purulent pneumonia in calves after parainfluenza-3 virus and P. haemolytica exposure. This was achieved using much smaller inocula than in experiments previously reported.