Bovine Viral Diarrhoea (BVD)

It is estimated 90% of UK herds have been exposed to the bovine viral diarrhoea virus (BVDV), with industry research showing in 2015 46 percent of dairy cattle and 44 percent of beef cattle tested antibody positive for BVDV.

The effect BVD has on an animal depends on its age, whether the animal is pregnant and the strain of the virus. Symptoms include poor fertility and abortion, milk drop, congenital deformities and poor calf health, including immune suppression and diarrhoea.

The greatest impact is seen in naïve and pregnant cattle. Infection of a naïve cow in the first 120 days of gestation may lead to the birth of a persistently infected (PI) calf. This is caused by BVDV crossing the placenta and, due to the immaturity of the calf’s immune system, the virus is recognised as ‘self’ and not eliminated. PI calves can appear normal, but they will shed BVDV throughout their lives, and are a major source of BVD risk.

The fundamental principle of BVD control is to find and remove PIs and to prevent PIs being born. Initiatives to control BVD are underway across the UK.