Calf serology on 59 UK farms known to have had a history of respiratory disease issues (2021 to 2022) reported 91.5 percent of samples being positive for bovine coronavirus (BCoV).
Speaking at the National Youngstock Conference, Dr Kat Baxter-Smith from MSD Animal Health UK suggested coronavirus needed to be taken more seriously as a respiratory pathogen by veterinary practitioners and the UK cattle industry – just as human health experts have had to change their mindset following the COVID-19 pandemic.
Calf respiratory disease is widespread (described as inevitable by some farmers) and comes at a high cost from an emotional and business productivity perspective.
It’s a classic iceberg disease and one which is continually highlighted as a critical area for overuse of antibiotics.
Despite this background, there is an under use of vaccination in the UK cattle sector.
“While BCoV is a relatively well-known cause of neonatal calf diarrhoea – and the same virus as the respiratory variant – its role and impact in calf pneumonia has been less well defined,” said Kat. “However, our last diagnostic data certainly shows its overwhelming presence during calf respiratory disease outbreaks in the UK.”
Kat explained that there may be a link between initial respiratory infection and intestinal infection because the virus is produced in the respiratory tract and then swallowed with the copious quantities of mucus generated during infection.
“Indeed, an association has been shown recently between detection of BCoV in calf faeces and detection of BCoV in cases of pneumonia on the same farm,” she said.
She added that the fact bovine coronavirus is frequently isolated alongside other, perhaps more recognised respiratory isease pathogens such as BRSV, Mannheimia haemolytica, Pi3 and Mycobacterium bovis, suggests an interplay between these organisms.
“Research has already shown that BCoV infection disturbs the protective mucus lining of the thoracic tract. It may, therefore, be that BCoV opens the door for the other viral and bacterial pathogens to establish themselves and cause disease,” she explained.
“While the pathogenicity of BCoV within the BRD complex remains an unknown quantity, its ubiquitous presence in the UK cattle population – and the recent human experience of coronavirus as a significant respiratory pathogen – suggests the need for some re-evaluation.”
“Calf respiratory disease is a multifactorial complex with a range of inciting pathogens often implicated. Consequently, to maintain effective control, it is important for farmers work closely with their vet on the development and implementation of a bespoke action plan for their own farm situation,” recommended Kat Baxter-Smith.
“Maximising a calf’s own ability to resist disease by focusing on excellent colostrum management combined with a robust vaccination programme is key.
“Essentially, the focus for modern calf rearers should be immunity-led disease prevention – and that’s where the input of a good vet is priceless.
“For example, the vet can quickly help you identify the pinch points – or key disease risk areas/weaknesses – in your system, whether during or shortly after calving, in the individual or group rearing pens, at weaning or in the later growth stages.
“Calves can suffer pneumonia lesions to their lungs from as young as two weeks of age, so early and appropriate vaccination against respiratory disease can often tip the balance towards more effective control,” said Kat.
