A natural outbreak of bovine respiratory disease caused by bovine respiratory syncytial virus.

An outbreak of respiratory disease occurred in a herd of 34 calves and 5 cows in a barn. The disease which affected 24 calves and 1 cow, was characterized by coughing, fever, anorexia, nasal discharge and pulmonary rales. Two calves died 5 days after the disease outbreak and were necropsied. Bronchitis, bronchiolitis and alveolitis were among the lesions observed in these calves. Bovine respiratory syncytial virus was detected, in lung sections of the dead calves and also in nasal washings of some of the calves and one cow, by the direct fluorescent antibody technique and/or cell culture method. Seroconversion to the virus was detected in most animals tested.