Schmallenberg and Bluetongue at lambing time
Bluetongue, Disease information
Scanning and lambing are stressful, busy times for vets and farmers, even more so when things go wrong. At these times it is still imperative to use evidence to guide our thinking and actions. The Bluetongue (BTV) and Schmallenberg (SBV) viruses have dominated so much of our thoughts and conversations in the last few months. Even so, where they are suspected, testing for these viruses is essential, not only for national surveillance purposes, but also for animal health and welfare.
Active infection with certain BTV serotypes or SBV have been associated with increased barren rates in ruminants and birth deformities. In the UK BTV3 outbreak, such clinical effects on reproduction have been confirmed in cattle, in or near the restriction zone in England. We are hoping that vaccination will help to mitigate some of these impacts as we go forward.
For SBV, predicting and controlling infection is difficult, as there are currently no commercially available vaccines. However, flocks appear to suffer from clinical disease only once every few years. This is due to the protective immunity gained after infection, and disease is not seen again in these flocks until a high proportion of ewes have been replaced with naïve animals. Over the last few years, we have seen SBV affecting flocks in different parts of the UK, spreading west and north over subsequent lambing cycles. This year, so far, the number of farms affected has been low compared with the last two years, but some individual farms have suffered significant losses. These devastating losses correspond to success in achieving a tight lambing and the unfortunate incursion of SBV in midges when most ewes were 25-50 days pregnant.
In cases of high barren rates or lamb deformities, we urge vets and farmers to investigate the cause, ruling out non-BTV/SBV causes, to ensure the correct control measures are put in place.
Useful resources for more information:
Bluetongue virus 3
- https://ruminanthw.org.uk/bluetongue-virus-information-for-vets/battlebluetongue-vet-information/
- https://ahdb.org.uk/bluetongue
- Brain lesions in BTV‐3‐positive calves in England – Swinson – 2025 – Veterinary Record – Wiley Online Library
Bluetongue is a notifiable animal disease. If you suspect it, you must report it immediately by calling the Defra Rural Services Helpline on 03000 200 301. In Wales, contact 0300 303 8268. In Scotland, contact your local Field Services Office. Failure to do so is an offence.
Schmallenberg virus