Pathogenesis and clinical signs: Isolates vary in virulence. Cessation of ciliary beating and epithelial necrosis predispose to secondary bacterial infections and coughing.
Calf pneumonia is a complex respiratory disease probably associated as much with management (crowding, low ventilation, high humidity, colostral deprivation, transport stress, mixing of stock from differing herds). The agents are : PI-3, bovine respiratory syncytial virus, infectious bovine rhinotracheitis virus, Mycoplasmata and Pasteurellae. Shipping fever occurs in beef cattle after long journeys.