Bovine Viral Diarrhoea, BVD, is a disease that affects cattle. Calves born to cows exposed to BVD during pregnancy can be born PI’s (Persistently Infected animals). PI animals carry and spread the disease throughout their lives, without necessarily showing any signs of illness themselves. TI (Transiently Infected) animals have the disease and will recover, but are temporarily contagious while sick. They too will spread the disease.

BVD is most commonly transmitted by direct contact with PIs and TIs or ingestion of faeces containing the virus. Other causes of spread can be via contact with semen, milk, saliva, urine, placenta or birth fluids. BVD virus may also be spread by transportation, yards, equipment, footwear and can survive in the environment for up to seven days.

BVD infection in adult dairy cows can cause reproductive wastage, weight loss and reduced milk yield, and a compromised immune system which may not protect them from other infections. BVD has a major impact during mating and pregnancy causing infertility, embryo loss, abortions, stunted and deformed calves and the birth of dead calves. The outcome of exposure to BVD depends on the stage of pregnancy at the time of infection.

An active infection in a dairy cow can last two to three weeks and reduce milk production by up to 10%.

In later stages of pregnancy first time exposure to the disease can cause the calf to be born a PI, which will carry and spread the disease for life.

80% of PIs die in the first 18 months; death is unavoidable and costly. These deaths often go undiagnosed and symptoms are often blamed on other conditions such as parasitism.

In New Zealand, about 80% of herds have had exposure to BVD and around 15% have active infection at any one time.

Vaccinating naive stock prior to first mating and annually prior to consecutive matings will stop the birth of new PIs. By vaccinating and adhering to a control programme it is possible to break the BVD cycle.

Contact your Veterinarian to discuss vaccinating for BVD and forming a management plan for your farm.