New screening data has highlighted the importance of protecting calves against bovine coronavirus as part of a wider strategy to prevent bovine respiratory disease (BRD).
Analysis of 1,732 calves screened through MSD Animal Health’s BRD screening service between 2022 and 2026 found that 69.5% had antibodies to bovine coronavirus.
Coronavirus-positive groups were also significantly more likely to show evidence of other respiratory pathogens, particularly bovine parainfluenza virus type 3 (PI3) and Mannheimia haemolytica. Each additional PI3-positive calf was associated with an approximately 37% increase in the odds of a group being coronavirus-positive.
“Seeing evidence of multiple pathogens within the same groups reinforces that BRD is rarely caused by a single pathogen. It highlights the need for farmers to take a proactive, whole-farm approach to respiratory disease prevention,” said MSD Animal Health veterinary adviser Dr Kat Baxter-Smith.
Bovine coronavirus may play a role early in the disease process by affecting the protective lining of the respiratory tract, potentially making it easier for other pathogens to contribute to disease.
Protection against respiratory coronavirus can start from day one, with Bovilis Nasalgen-C, an intranasal vaccine that can be administered to calves from the day of birth. It is licensed to reduce clinical signs of upper respiratory tract disease and nasal viral shedding associated with bovine coronavirus infection.
“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.
Importantly, the absence of obvious respiratory signs does not necessarily mean calves are healthy. While clinical BRD typically affects around 11–16% of calves, subclinical disease, where lung damage occurs without obvious signs, may affect 23–67%.
“By the time coughing, nasal discharge or increased respiratory effort become apparent, lung damage may already have occurred,” said Dr Baxter-Smith.
Even small lung lesions can affect performance, with research showing calves with 1–2cm lesions can have average daily gains 96–138g lower than calves without lesions.
“This is why understanding which pathogens are circulating and identifying risk factors on farm is so important,” added Dr Baxter-Smith.
“Vaccination, alongside good colostrum management, nutrition, housing, ventilation and hygiene, can all contribute to reducing the risk of respiratory disease.”
Prevention starts before disease strikes
BRD screening can help identify pathogen exposure and potential gaps in protection, while thoracic ultrasound (TUS) can identify lung damage and subclinical disease.
MSD Animal Health offers vaccines covering key BRD pathogens, including respiratory coronavirus, BRSV, PI3, M. haemolytica and IBR.
“Vaccination is not a silver bullet for respiratory disease, but it is an important part of a wider prevention strategy,” said Dr Baxter-Smith.
“BRD results from a combination of infectious challenge and other risk factors, so prevention needs to focus on both reducing exposure and supporting the calf’s ability to withstand disease.”
With respiratory disease often becoming more challenging during the autumn and winter months, farmers and vets are being encouraged to review their BRD prevention plans now, ahead of winter housing, and consider whether current vaccination and management strategies are providing adequate protection.
BRD webinar
MSD Animal Health will be exploring the latest thinking around BRD in a webinar on Monday, September 14, featuring a farmer who is actively using thoracic ultrasound scanning as part of BRD management. Find out more and register here.
