Clinical signs following experimental lungworm infection and natural bovine respiratory syncytial virus infection in calves

Similar clinical signs have been reported in calves infected either by Dictyocaulus viviparus or bovine respiratory syncytial virus. Three experiments were carried out to establish the clinical picture and the course of the disease in animals with these infections. The clinical signs of calves infected with lungworm included coughing, nasal discharge, tachypnoea, abdominal breathing and pyrexia, and auscultation of their lungs revealed increased bronchial sounds. Similar signs were also observed after infection with bovine respiratory syncytial virus, but the signs were more acute and resolved more rapidly than in animals infected with lungworm larvae. Calves infected with lungworm had more serious clinical signs after infection with bovine respiratory syncytial virus than calves, which were not infected with lungworm.