Infectious bovine rhinotracheitis (IBR), parainfluenza type 3 (PI 3), bovine respiratory syncytial (BRS) and bovine coronavirus (BCV) infections are common viral diseases of cattle (Anon, 1990). IBR, PI 3 and BRS viruses have all been incriminated as causes of bovine respiratory disease (Anon, 1990). BCV is one of the agents that causes diarrhoea and occasionally respiratory tract infections of calves and is associated with winter dysentery in adult cattle (Wegeet al., 1982).