BVDV: Pest of a virus for cattle

Pestivirus, also known as bovine viral diarrhoea virus (BVDV), is an often-overlooked disease when it comes to cattle production in Australia. It is estimated that BVDV costs the Australian cattle industry $114 million annually. Overseas, in countries such as Germany and Switzerland, they have managed to eradicate the disease from their cattle populations.

What is pestivirus?

Pestivirus mostly affects cattle and sometimes sheep. Symptoms vary depending on the time of infection. Offspring may be born persistently infected (PI) if the mother is infected during early pregnancy and the foetus survives. The PI calf’s immune system does not recognise the virus as foreign and therefore doesn’t eliminate it. There are many different strains, but the most common in Australia is the BVDV-1c strain, which makes up 97 per cent of cases.

How is it spread?

Pestivirus is spread by direct contact and also contact with secretions of infected animals. It can also be spread across the placenta from an infected cow to its calf.

Infection in non-pregnant cattle is usually mild. The most severe consequences occur if cattle are infected in early pregnancy. This means the greatest risk is introducing new cattle that are shedding disease to pregnant cattle with no immunity.

Clinical signs

Clinical signs of pestivirus in cattle may include:

Diagnosis

Diagnosis is based on a recognition of clinical signs that are consistent with a pestivirus infection.  Laboratory testing is then used to confirm the diagnosis. Samples for testing can include blood, foetal fluid, ear notches, nasal swabs and milk samples.

Management and prevention

The critical thing to do is determine whether your herd has a problem with pestivirus. The best way to do this is to have a vet to collect samples for testing. If pestivirus is found to be present in the herd, then it is important to remove all the persistently infected cattle as they are a constant source of infection.

Preventing the disease in the first place is also pivotal. Quarantine of new cattle will assist in determining the health status of these individuals and blood can be submitted to determine the status. Quarantine should be a mainstay in your livestock management plan regardless, to prevent a multitude of other possible diseases that could infect your herd.

Vaccination

A commercial vaccination is available in Australia, called Pestigard®. It covers cattle for the BVDV-1a and BVDV-1c strains of pestivirus, meaning that the main strain found in Australia is covered in the vaccine. The vaccine costs around $5 per dose and dosing requires two doses 4-6 weeks apart and then an annual booster from there. Additionally, a dose of the vaccination can be given before joining to ensure immunity in early pregnancy and decrease loss.

For more information and advice, contact the Murray District Vets on (02) 6051 2200 (Albury) or at (03) 5581 9900 (Deniliquin)