Increasing liver fluke risk poses a threat to in-lamb ewes

Liver fluke infection poses a continued risk to adult pregnant sheep and could lead to reduced health and abortion, says Roger Daniel, Vet Lab Agency, Camarthen.

“The VLA has continued to see severe liver damage as a result of fluke infection from adult and late immature liver fluke.”

Following three wet summers in a row, the risk of liver fluke infection has remained high in most areas of the UK.

And even sheep treated in the autumn are still at risk. “Ewes that received treatment in the autumn may have picked up infection from grazing up until the extreme cold weather in December.”

Fluke larvae can survive at and around freezing, but recent cold temperatures should have killed off most larvae at pasture, he says.

“From December onwards, ewes shouldn’t have picked up any new infection, but there is still the potential for ewes to carry through earlier infection to housing.

“The concern is heavily pregnant ewes could be harbouring infection.”

And with liver fluke infection causing overall health issues which could cause abortion, the problem is not one to be taken lightly. “Clinical signs in sheep presented to the VLA have included anaemia, rapid condition loss and sudden death.

One autumn treatment is good, but ewes should be treated at housing with a broad spectrum product capable of killing all stages of fluke. “When ewes are not treated for a second time, there is the potential for immature fluke to mature at housing,” stresses Mr Daniel.

Sheep farmers should look carefully for signs of the disease and consider treating ewes again. However, it is essential producers consult their vet on which product to use and whether it is safe to treat heavily pregnant ewes, he says.

“I would also recommend farmers sending in a sample of 10 faeces samples to the VLA for fluke analysis.”

And independent vet consultant Tony Andrews also emphasises the need for farmers to check it is fluke they are dealing with before dosing ewes. “There is no doubt fluke is more widespread than it has been before, with many eastern counties which would historically be fluke free,now affected by the problem.

“However, despite this and the recent wet summers it is essential to be sure before treating. With in-lamb ewes it will be the added stress of penning and dosing which is the issue. Any handling of in-lamb ewes should be avoided unless totally necessary. Where ewes have to be treated for fluke it may well be worthwhile doing it at the same time as any other handling, such as crutching, to avoid repeatedly handling them.”

But, flukicides themselves are perfectly safe for pregnant ewes, he says. “However, where ewes are within six weeks of lambing take extra care and consider whether dosing could wait until after lambing, particlularly when ewes are due for multiple lambs.”