The BVD ear tag test can identify PI calves at birth – they and the virus can immediately be removed from circulation. Unfortunately, in the third year of the AHI eradication scheme, we are seeing policy loopholes that are enabling the virus to evade us.

One client’s experience clearly illustrates the problems. Last May, while retesting three PI calves by blood test, we were able to deduce the source of the infection on this farm; they had been clear the previous two years.

These calves’ dams had been pastured on land adjacent to a farmer with a BVD problem. The neighbouring farmer was unaware of the problem the previous summer, but following his routine autumn TB test, we identified a two-year-old bullock which looked like it had mucosal disease.

We blood-sampled it and having tested positive for BVD virus, it was removed from the herd. It should be noted that this animal was born before the BVD scheme commenced and its owner had been previously unaware of its BVD status. Once he became aware of it, he immediately removed the animal.

Unfortunately, this was too late for these three calves who had been infected across the boundary fence while still in their mother’s wombs.

Before I departed, the farmer’s wife said she felt it didn’t make sense to allow infected calves to stay on farms for a whole month to be retested on the slim chance that some of them might prove false positives.

Nobody had ever commented on this aspect of policy to me before and unfortunately her words proved very prescient. This spring, they have had two more PIs and we can date their time of infection specifically to the dates the original calves were kept for retesting. The science behind a policy of immediate, compulsory removal of PIs is incontrovertible. This farmer’s experience and his wife’s common sense clearly demonstrate the need for us all to re-examine what we are doing with our PIs.

*Conor Kilcoyne owns and runs Kilcoyne Veterinary, Wolfe Tone Square Tubbercurry, Co Sligo. Kilcoyne Veterinary is part of XLVets. XLVets is a group of progressive practices working together to achieve a better future for agriculture and veterinary in Ireland. Visit www.xlvets.ie