Most cattle producers these days have heard of pestivirus and it’s certainly front of mind for many when you’ve had a poor preg testing result or are experiencing abortions in your herd.
Pestivirus is known by several namesbovine viral diarrhoea virus, BVDV, ‘pesti’ and mucosal disease – but these all refer to the one virus. The virus is spread by persistently infected cattle, commonly referred to as ‘PI’s’. These animals are born as a PI and secrete the virus is all their bodily secretions - urine, faeces, saliva… everything. Direct contact with a PI is the main may way the virus is spread. While we think many PI’s succumb to other diseases in the first few years of life, we know some survive for much longer and they can even go onto get pregnant and give birth to their own PI calf.
The biggest risk pestivirus poses to any herd is if animals are exposed to the virus for the first time when they are pregnant and have no immunity. Depending on what stage of pregnancy an animal is, the infection can result in early pregnancy loss (which is usually picked up by a poor preg testing result), abortions, birth defects and the birth of weak calves that fail to thrive. This is also how a PI is born – when the mother is infected for the first time at a particular stage of pregnancy (day 45-125).
So, what can you do to protect your herd? Pestivirus control is all about knowing the level of immunity in your herd. For most larger producers this can be achieved by doing a blood test on about 10 heifers well before joining. If you’ve never done any testing before, its recommended to test some older age groups at the same time. Once you know the level of immunity in your herd you can decide whether or not vaccination is required, and of which age groups. Natural immunity is lifelong and fortunately the blood test is able to differentiate between immunity from natural exposure and immunity from the vaccine. This means we can recheck natural immunity and re-assess vaccine requirements after commencing a vaccination program. As it costs as much to test 10 heifers as to vaccinate 20, small producers may be better off to simply vaccinate.
If you would like further information or to chat about any animal health issues, please feel free to contact your local District Veterinarian’s: Em Johnstone (0419 334 077) or Evie Duggan (0427 147 939). Or call 1300 795 299
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