Schmallenberg - Confirming a Diagnosis

As the spring lambing and calving period progresses there have been many reports across the UK of deformed lambs and calves - suggestive of in utero infection with Schmallenberg virus (SBV).

Our Dumfries veterinary centre has confirmed the diagnosis in numerous cases, all of which have been in northern England or just on the Border but we are aware of anecdotal reports of many more cases. 

There has been a case reported in the Scottish Borders so it is quite likely that there will be further cases in Scotland.      

 

An updated list of confirmed SBV cases is available at APHA’s Vet Gateway

 

A few things to consider are as follows:

  • Vet practitioners are in an excellent position to know what the SBV situation is within their area as many of the deformed lambs and calves will need veterinary intervention at parturition
  • We now know that SBV vaccine production is in progress again with the expectation that vaccine will be available later in 2017, hopefully before the start of the pedigree sheep breeding season
  • This raises the importance of making a laboratory diagnosis of SBV as the cause of congenital deformities to inform future control strategies

 

There are other differential diagnosis of the arthrogryposis/hydranencephaly syndrome seen following in utero SBV infection which include:

  • Breed related disorders
  • Plant and other chemical teratogens
  • Pestivirus infection
  • Protozoal infection (Neospora caninum)
  • Bluetongue virus infection (hydranencephaly in the absence of arthrogryposis)

 

Some diagnostic considerations are as follows:

  • The best way to consider the full range of possible differential diagnoses is to submit the entire lamb or calf for PM examination - SBV testing would be carried out at no additional cost as part of the full examination
  • Diagnostic options for SBV are constantly evolving and we have recently received updated information from German labs which suggests that sampling either a piece of the umbilicus or a placental fluid scrape (see below) gives the best PCR positive rates for SBV - this makes sampling quick, simple and achievable on farm and we would recommend this sampling method
  • Conversely, a negative maternal SBV serology result is the most efficient means of excluding a diagnosis of SBV malformation in her offspring, so a maternal blood sample is also useful

 

If you wish to discuss suspect cases and the best diagnostic options, please do not hesitate to contact us

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