New screening data has exposed the scale of bovine coronavirus exposure in UK calves, increasing pressure to strengthen respiratory disease prevention before winter housing.
More than two-thirds of calves screened by MSD Animal Health between 2022 and 2026 found 69.5% had antibodies to bovine coronavirus. Those calves were also more likely to show evidence of other respiratory pathogens.
Subclinical bovine respiratory disease can damage lungs and reduce growth, while mixed infections mean vaccination must sit alongside colostrum management, nutrition, housing, ventilation and hygiene.
“Vaccination is not a silver bullet for respiratory disease, but it is an important part of a wider prevention strategy,” said Kat Baxter-Smith, veterinary adviser at MSD Animal Health.
Bovine coronavirus may act early in the disease process by affecting the respiratory tract’s protective lining. This could make it easier for other pathogens to contribute to disease.
Clinical BRD typically affects about 11-16% of calves. However, research cited by MSD suggests subclinical disease may affect 23-67%, with lung damage developing without obvious signs.
“By the time coughing, nasal discharge or increased respiratory effort become apparent, lung damage may already have occurred,” said Dr Baxter-Smith.
Even small lesions carry a performance cost. Calves with lesions measuring one to two centimetres recorded average daily gains 96-138g lower than animals without lesions, according to research cited in the release.
Early checks
Blood screening can identify pathogen exposure and possible gaps in protection. Thoracic ultrasound can detect lung damage and subclinical disease before farmers see clear respiratory signs.
MSD subsidises bovine respiratory disease screening through most GB veterinary practices. The service tests blood from a small selection of calves aged three to six months for exposure to five major pathogens.
The company also markets vaccines covering respiratory coronavirus, BRSV, PI3, M. haemolytica and IBR. Its Bovilis Nasalgen-C intranasal vaccine can be given from birth and is licensed to reduce upper respiratory disease signs and nasal viral shedding linked to bovine coronavirus.
“For farms where coronavirus is identified as part of the respiratory disease challenge, having the option to protect calves from the day of birth can be an important part of a wider prevention strategy,” said Dr Baxter-Smith.
The screening analysis found that each additional PI3-positive calf was associated with an approximate 37% rise in the odds of a group being coronavirus-positive. The result supports a whole-farm approach because rarely one pathogen is involved.