Epizootiologic Studies of Shipping Fever of Cattle: I. The Microbial Agents Isolated.

Nineteen strains of Pasteurella spp., but no viruses cytopathogenic for bovine embryonic kidney cells were isolated from pneumonic lesions present in "normal" veal calves at slaughter. In studies on two herds of native cattle and six lots of western feeder calves, Pasteurella spp. were isolated from nasal swabs from healthy cattle and those with shipping fever. Viruses of the psittacosis-lymphogranuloma group were isolated from nasal swabs from animals in five groups. Viruses provisionally identified as bovine enteroviruses were isolated from nasal swabs of calves in two lots. There was serologic evidence of a temporal association of myxovirus para-influenza 3 (PI3) with shipping fever in three lots of calves. From two of these three lots, strains of PI3 were isolated from ten animals, four of which had clinical shipping fever at the time of virus isolation.