By Emma Rooke, Livestock Biosecurity Network
PESTIVIRUS is one of the most important production diseases in the Australian cattle herd, but it can be easily diagnosed and the risk of introduction into the herd can be reduced using some simple biosecurity steps.
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.
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.
The costs of the disease are estimated at 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, Pesitivirus causes a mild transient infection from which cattle recover.
However, if females are infected during pregnancy, BVD can cause abortion, still birth, birth deformities or calves that remain persistently infected for their entire life.
These persistently infected (PI) animals are the main source of infection to the rest of your herd.
They are virus factories that excrete huge amounts of virus for their whole life, and are a constant source of infection to other cattle.
PIs are often, but not always, sickly animals that tend to die before two years of age.
On a positive note, Pestivirus can be managed to reduce its impact on your breeding herd, and some simple steps can reduce the risk of the virus from entering your herd in the first place.
A good place to start is to find out the BVDV status of your herd or breeders.
Talk to your vet about testing the immune status of your most vulnerable females, heifers, well before joining 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 include identifying and removing PIs, 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.
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 a simple and inexpensive ear notch or hair test before they are introduced to the property (again, speak to your vet about how you can do this)
• Isolate new stock for at least 28 days before introducing to your resident herd
• Prevent your cattle from having nose to nose contact with neighbouring cattle.