The national BVD eradication programme is progressing well with the rate of PI calves born reduced to 0.09%. On an individual farm level, this news is to be welcomed, but it is of little comfort when a breakdown occurs.

Animals that come in contact with BVD after birth become transiently infected for three to four weeks and subsequently become immune for life. If the animal is naïve (susceptible) and pregnant, she may produce a PI calf.