Schmallenberg ravages hundreds of flocks in Southern England

A mild autumn and low immunity in sheep are cited as key reasons for the increased numbers of deformed lambs caused by Schmallenberg.

As the number of flocks lambing grows with spring approaching, one Somerset vet fears the current number of cases at the start of the lambing season is only going to escalate further.

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Heather Marie Niman, a vet with Tibbs and Simmons in Bristol, said, “So far we feel this is the worst year we can all remember ever experiencing with Schmallenberg. Since our sheep clients started their lambing season in December, we think we have had between 30 to 50 cases in lambs but so far only one in cattle.

“For context, in the winter of 2016/17, which saw the last significant wave of the disease, the APHA confirms there were 97 farms confirmed affected across the whole of England between December and May, and by the end of the year that had risen to 137 farms in England and Wales and 9 in Scotland; in the Borders, Dumfries and Galloway, Ayrshire, and parts of Lanarkshire.

"It would seem that this year, with the number of deformed lambs in our practice alone, the flocks affected will be much higher in number and currently it is just the start of January. Most of the flocks in the practice who have started lambing have had multiple cases suggesting the disease. We all worry this is only going to escalate, as the warm weather the midges need continues into November in this area so it’s almost certain we’ll see more cases as more of the flocks, including those on the colder Mendips, start to lamb later in the season.

“I first started seeing the disease in practice over ten years ago when it was first diagnosed. The number of animals affected comes in waves, as after an outbreak, herds and flocks build up good immunity for a period. In sheep, where the population ages and replaces more quickly, this means flock immunity drops after a few years and in the right weather conditions are susceptible to the disease again.

“Here, the practice last saw a jump in numbers in 2016, i saw a few cases again in 2020, while 2022 had very few cases due to the drought and extremely high temperatures down here, a combination of factors the midges would have found very challenging.”

Vet Heather Marie Niman

Identifying the disease in this area is greatly aided by the Bristol University Post Mortem Services laboratory, which runs postmortems of lambs and calves under the free testing scheme. Dr Niman said the vet practice and their clients are delivering several sets of lambs for tests at the moment.

“I think for farms who may not have seen the disease before it’s important to know the signs; most commonly here we are seeing deformities of the legs, sometimes shortened but mainly twisted and fixed, combined with twisted spines. Necks can be fixed behind or under the lamb too and we see a very shortened bottom jaw on most lambs, which is uncommon in other causes of deformities.

"Keeping in mind what you might be facing when you put your hand inside to assist a ewe is really really important because whilst most can be delivered, especially in multiple births, we all want to minimise any damage to the ewes so they can breed again next year; so more lubrication, patience, and pain relief after assistance will be really beneficial.

"Sadly, whilst most are born dead, lambs can be born alive but with deformities particularly in the hind limbs. I find these particularly sad as they are often keen to suck and survive at the front end, but need to be put to sleep immediately. A small number are so severe that a caesarian is required to remove a twisted and fixed lamb.”

The practice covers from North Somerset to Glastonbury in the south, supporting over 400 farms, both commercial and pedigree, across dairy, beef, and sheep.

The disease is transmitted through bites from infected, and creates these deformities when animals are infected during the mid stages of pregnancy; about four to eight weeks into gestation. Ewes lambing at the moment would have been served in the middle of August and so been susceptible to the disease from mid-September to mid-October.

Worryingly, local temperatures into the majority of November were over ten degrees Celsius, with a temperature of 14 degrees recorded only a couple of weeks before Christmas.

There is no commercially available vaccine at the moment, and the current situation is that there would need to be significant industry demand for one to be produced. High levels of immunity in animals in the years following an outbreak make farmers reluctant to pay for a vaccine. This is part of the reason there have been fewer cases reported in cattle.

Jonathan Long, who farms at Bishops Frome in Herefordshire, added: “We’ve seen a few cases so far, and a number of other farms locally and further into southwest England have seen it too. Scanners locally are reporting dead or dying embryos at scanning, and we had an unusually high number of barrens when we scanned the Jan lambers back at the end of October.

Sheep farmer Jonathan Long

“We have 235 ewes due to lamb in March and April to scan on Monday, which I’m now nervous about. Some of those are the barrens from the earlier scanning. We’ve had six so far from 36 ewes to date. Anecdotally I’ve heard of others worse affected, and it is gut-wrenching to deal with as you know you have no hope of the lamb being viable when you lamb the ewe.”

Stephen Stamp, who runs a pedigree flock of 120 sheep at Bowridge Farm in Somerset, has had six cases so far from a batch of 20 pedigree Charolais ewes and shearlings.

He said: “We lambed the Dorset Downs in December, and there were no issues, but in the Christmas week, we had problems with the shearling ewes. I know a farmer in the area has had over 40 suspected cases from a bigger flock.

Stephen Stamp

"We have our Texel and Bleu de Maine flock to lamb in March, and it is a worry for us. We are finding you get one good lamb, but the next one is a mess, all deformities. A lot of the lambs are born alive but don’t survive for long as they are badly deformed. Our older sheep seem to be okay, but the younger ones are getting it. It was a mild and wet autumn here, and we had a fly strike affecting sheep in November, which is later than we have had before.”

The disease is transmitted through bites from infected, and creates these deformities when animals are infected during the mid stages of pregnancy; about four to eight weeks into gestation. Ewes lambing at the moment would have been served in the middle of August and so been susceptible to the disease from mid-September to mid-October. Worryingly, local temperatures into the majority of November were over ten degrees Celsius, with a temperature of 14 degrees recorded only a couple of weeks before Christmas.