Outbreak of shipping fever associated with several pathogens in grazing calves.
Respiratory disease, characterized by pyrexia, depression, nasal discharge and cough, occurred in some of 254 Holstein calves one week after being put on pasture and one subsequently died. Mycoplasma bovirhinis, Pasteurella multocida, Pasturella haemolytica and parainfluenza virus type 3 were isolated from the affected animals. The results of serological tests on paired serum samples showed a significance rise in antibody titres against not only these organisms but also against bovine viral diarrhoea-mucosal disease virus. PM examination revealed focal pneumonia and whitish pseudomembranes in the paranasal sinuses of the animal that died. Histologically, acidophilic cytoplasmic inclusion bodies were observed in the epithelial cells of the paranasal sinuses. The disease was diagnosed as shipping fever caused by mixed infection with parainfluenza type 3 virus and other pathogens.