Epizootiologic Studies Of Shipping Fever: II. Exposure Of Calves To Pasteurellae and Para-lnfluenza 3 Virus.

In four trials, the exposure of six calves to various stressors and an aerosol of pasteurellae did not evoke significant responses. In ten trials, 20 calves were exposed by aerosol or intratracheal injection to myxovirus para-influenza 3 (PI3) alone or combined with pasteurellae. A respiratory syndrome similar to that observed in mild cases of shipping fever was regularly reproduced in calves which had low serum hemagglutination titers to PI3. One calf developed a severe bronchopneumonia, was killed and the virus was reisolated from its lungs. Exposure to P13 plus pasteurellae usually resulted in an increased nasal discharge. The stressors employed in a few trials did not significantly alter the response.