After plenty of discussion about Bluetongue in the early part of this year, things may seem to have gone a little quiet and many may be wondering just what is going on.
Recent discussions and webinars with vet colleagues and APHA staff in the Southeast have shown some surprising and sometimes conflicting information from farms which have been infected with the virus. Some report typical clinical signs in cattle, with milk drop and mini abortion storms. Others indicate a wide range of clinical signs in sheep, from very few signs, to 30% of the flock affected and 5% additional losses. Certainly, the effect of the virus within herds and flocks appears varied, dependent on many aspects, some of which are outside of our control. It is therefore not clear what is on the horizon for us in the Southwest.
There are a few things to consider:
We are still in the ‘low vector’ season, but the risks will increase from Summer through to Autumn. This means that although temperatures have warmed and midges are now active, there has not been sufficient time for both the midges and the virus to replicate. This means that there is likely to be a lag between temperatures warming and virus spreading. As the summer continues the potential risk increases of new infections arriving with infected midges blown over from Europe.
Bluetongue infection can cause infertility. One of the main clinical signs associated with Bluetongue is an increase in body temperature. Although this may be missed if there are no other signs, this can have a major impact on sperm production. A slight increase in temperature can knock out sperm and lead to temporary or persistent infertility. Sperm production takes 8-10 weeks to complete and so if Bluetongue infects a naïve bull or ram in the run up to the mating season this can have devastating impacts on herd and flock performance. Vaccination of male breeding stock is particularly worth considering, especially in early or seasonal breeding flocks and herds where bulls and rams are less likely to have come into contact with Bluetongue.
Vaccination and changes to restriction zones. We have seen some fantastic vaccine uptake across the practice. Breeding stock vaccinated ahead of lambing or calving should still have protection, but it is worth considering vaccination for naïve animals such as fattening stock and replacement heifers and ewe lambs if they have not been done already. Recently announced changes to the BTV restriction zone, to include the whole of England from July onwards, mean that vaccination is the main way to protect your stock once England wide movements begin again and pre movement blood testing is stopped. If you would like to discuss vaccination, please get in touch with us and we will be happy to chat this through.
Be vigilant and keep up to date. Ensure that you know the clinical signs of Bluetongue in your stock and consider atypical signs too. Bluetongue is a notifiable disease and so any suspicion should be reported to APHA. You know your animals the best, and don’t hesitate to get in touch if you notice anything untoward. Keep up to date with movement restrictions. There is a good website (Bluetongue: news, information and guidance for livestock keepers – GOV.UK) which will give up-to[1]date information for farmers and producers.
Written by Nicky Ogden BVM BVS MVM MRCVS
