BVD – still living in the Blackmore Vale!
Farmers and vets have been talking about BVD ‘bovine viral diarrhoea’ since the 1950’s but it still catches us out locally. If you have breeding cattle then you will have either opted to vaccinate your heifers and cows to protect the pregnancy, or together we may believe you can trust your biosecurity well enough that you will monitor your clear status.
If you choose to monitor then this needs to be robust so that you can rely on knowing if there has been a breakdown:
Dairies, do you quarterly milk test for antibody and check once/twice yearly for PCR virus?
Dairy and beef, do you do an annual youngstock screen of each and every management group of youngstock (9-18 months)?
Dairy and beef, if you ear tag and test, do you do all your calves? This varies across units of whether all are done including stillbirths, or just replacements.
A breakdown in one of our naïve beef suckler herds has been frustrating this year. Biosecurity appeared tight and annual youngstock screens were always negative. The first we knew of the virus introduction was a positive youngstock screen (positive on 4/12 bloods). The herd vaccinated straight away, and all animals were screened with ear tags with a positive yearling detected. A youngstock screen of one management group 6 months earlier had been clear. The calf crop of 2026 has all been ear tag and tested, the few positives were stillborn calves which would not have been tested on many farms. We now have assurance that all animals on farm are negative, and the vaccine is protecting the herd going forwards.
Another case in one of our dairy herds highlights how easily BVD can go undetected:
The herd had previously experienced BVD, with PIs identified and culled, and the herd vaccinated. Vaccination was subsequently stopped 13 years ago. Since then, occasional BVD PCR testing had been negative. A bulk milk antibody test in 2024 was slightly positive, prompting the farm to restart vaccination, but the 2025 booster was missed. This was picked up during the 2026 health plan – a useful reminder of the importance of thoroughly reviewing infectious disease control.
A youngstock screen found all five bulling heifers strongly positive for BVD antibodies. Using Animal Health and Welfare Pathway funding, a whole-herd PI hunt was then carried out, identifying four PIs shedding virus within the herd. The farm is now tag-and-testing all calves and has restarted a robust vaccination programme. Although the herd rears its own replacements, rarely buys in bulls and has few neighbouring herds, BVD can still enter via cattle contact, contaminated boots, clothing, equipment or vehicles.
The key message: don’t assume your herd is low risk. If you are not fully compliant with BVD vaccination, make sure your screening programme is robust. Bulk milk testing alone may not detect infection in youngstock quickly enough.
