Infectious Bovine Rhinotracheitis {IBR}

Infectious Bovine Rhinotracheitis (IBR)

Infectious bovine rhinotracheitis (IBR) is a viral disease caused by bovine herpesvirus 1 (BHV-1) that can also cause a mild venereal infection in adult cattle or a brain infection in calves. IBR is a highly contagious disease of the upper respiratory tract and can lead to serious primary or secondary pneumonia. The clinical signs of the disease are nasal discharge, fever and conjunctivitis. Acute disease in dairy cattle is usually accompanied by a severe and prolonged drop in milk production. Adult cows may also suffer from abortion and reduced fertility. Animals suffering from IBR are highly susceptible to secondary bacterial infections.
The exposure of cattle to BVH-1 has been known to be widespread in the UK since the 1960s (Dawson and Darbyshire, 1964), but the disease was generally considered unimportant as clinical signs were mild or rare. In the late 1970s, a more virulent form of the disease was reported (Wiseman et al., 1978), and it is believed that a more virulent strain of the virus entered the country (Edwards et al., 1990). In 1992, 34% of farms in the UK had one or more calves with antibodies against BHV-1 (Hogg, 1992). In 1996, some 70% of 360 tested dairy herds were positive for BHV-1 antibody in the bulk milk (Bennet et al., 2000).
Based on collated and unpublished data, it is suggested that the incidence of IBR outbreaks in beef and dairy herds in the UK has declined steadily between 1980 and 1995, in spite of low level of estimated vaccine use (Bennet et al., 2000).
Herds with IBR suffer mainly from low-grade problems associated with calf pneumonia, decreased fertility and occasional abortions. More serious problems are seen on farms that have not been exposed to IBR before. Outbreaks with milk-drop and fever in most cows and subsequent abortions and increase in calf pneumonia are seen.