Schmallenberg virus and abortion sampling

Be aware: Schmallenberg in lambing flocks this spring (and possibly spring calving herds)

We have recently confirmed abortion and or the birth of deformed lambs in several early lambing flocks due to Schmallenberg virus (SBV). SBV infection has been confirmed in flocks across the southern half of Scotland, including Dumfries & Galloway and Stirlingshire. A very large outbreak of disease has also been confirmed in Ayrshire, in a flock which would have been tupping ewes at the end of July into August. In this large outbreak the clinical signs were not always the “typical” malformations associated with SBV infection with lambs that appeared to have weak limbs and possibly also a lack of suck reflex or other neurological signs.

Mild weather continued into November resulting in a possibility that midges were flying and biting sheep late into the season. The situation will become clearer once more flocks start lambing. SBV infection could therefore also affect calving in 2025. SBV associated malformations can occur when viraemia occurs between day 28-56 of pregnancy in sheep and day 80-150 in cattle. 

What to do?

Nothing can be done now to prevent issues caused by SBV at an earlier stage of gestation. However, please consider SBV as a differential when investigating foetal deformities and barren cow or ewe problems. SBV serology can be added to screens of these animals, however, have it in mind that there is evidence that SBV antibody can persist for 6 years in cattle and 4 in sheep, so positive serology is not necessarily indicative of recent infection.

Notable foetal/neonatal pathology associated with SBV includes scoliosis, arthrogryposis and kyphosis, as well as brain deformities.  Any suspect cases should be sampled using the sampling list below or handed into an SRUC postmortem centre.

• Fresh brainstem (and full brain fixed if possible)
• Umbilicus / amniotic fluid scrape (simple samples, see below)
• Foetal fluid
• Fresh spleen
• Dam blood

These samples should be taken in addition to foetal stomach content, foetal fluid, fresh placenta and fixed tissues (brain, spinal cord, if possible, lung, heart, liver, spleen, placenta) if a full abortion investigation is required.

Collection of Amniotic Fluid from a lamb fleece

Bluetongue disease in foetuses – NB BTV is NOTIFIABLE

If the foetus has a dilation of cavitation of the brain, or evidence of cerebellar hypoplasia then one of the differential diagnoses that must be considered is bluetongue virus. Please do look at foetal brains and collate the movement history, then any foetal brains that have cavitation or other gross abnormalities should be notified to APHA.

Instructions for abortion sampling: please see our sampling guide srucvs-sampling-guide.pdf

Posted by SRUC Veterinary Services on 31/01/2025