Dr Kate Sawford, district veterinarian in Braidwood, has found pestivirus is the most commonly diagnosed cause of calf losses. 

These losses were associated with the purchase of in-calf heifers carrying calves persistently infected with the virus.

“I came across three cases over a period of three weeks,” Dr Sawford said. 

“These were mainly cases at a property level as opposed to individual cases.

“Pestivirus is one of the most common causes of stock loss for cattle producers in Australia. 

There was a study undertaken in northern Australia in 2014 and, before that, [a] study in 1967,” which found 61 per cent of cattle and 80 per cent of herds had the virus.

Pestivirus (also known as BVD, BVDV or mucosal disease) is primarily a reproductive disease, but also affects the immune system, leaving animals more susceptible to other diseases for the rest of their lives, according to Emma Rooke from the Livestock Biosecurity Network.

“There is no ‘one-size fits all’ approach for managing pestivirus but, given up to 90 per cent of Australian herds have the virus or have had it in the past, just about every herd would benefit from a systematic strategy to manage it,” she wrote in The Land on September 20, 2015.

“The costs of the disease are estimated between $15- $100 per breeder per year. It can be insidious and often goes undetected due to its subtle clinical signs, like poor reproductive performance, ill thrift and poor doers.

In pasture-based grazing systems, pestivirus causes a mild transient infection from which cattle recover.

However, if females are infected during pregnancy, BVD can cause abortion, stillbirth, birth deformities or calves that remain persistently infected for their entire life.”

Ms Rooke said some simple steps could be taken to reduce the instance of pestivirus on breeding herds.

“A good place to start is to find out the BVDV status of your herd or breeders,” she said. 

“Talk to your vet about testing the immune status of your most vulnerable females (heifers) ... so you can make some decisions about how to manage them during pregnancy.

You only need to blood test 10 per cent (minimum six animals) from each group as long as all animals have been running together for more than two months and are at least eight months old.”

Control methods for pestivirus included identifying and removing persistently infected (PI) animals using vaccine, using PIs to ‘auto-vaccinate’ others, or doing nothing (while understanding your risk).

“The cost benefit of introducing a control program will vary depending on your enterprise,” she said.

“Your vet can help you tailor a program to suit your enterprise.

To prevent introduction of the virus to your herd, use some basic biosecurity practices:

- Use a cattle health statement when buying cattle;

- Prevent introduction of PI animals, including bulls, by identifying them with an inexpensive ear notch or hair test before they are introduced to the property;

- Isolate new stock for at least 28 days; and

- Prevent cattle from having nose to nose contact with neighbouring cattle.

It’s a good idea to keep records and monitor herd health to detect subtle changes that might indicate that pestivirus has entered the herd, Ms Rooke said.

“Investigate poor reproduction performance, ill thrift or increased incidence of other diseases (such as scours or respiratory disease), which may be signs of pestivirus,” she said.

“If groups are managed separately then some groups may be affected and some not.

The more productive your enterprise, the bigger the impact pestivirus will have. 

So, talk to your vet and get some advice on the best approach to managing the risk of pestivirus in your herd.”