Farmers considering whether to treat livestock for liver fluke this autumn are being urged by experts from the Sustainable Control of Parasites in Sheep (SCOPS) and Control of Cattle Parasites Sustainably (COWS) groups to use the testing available to decide if they need to treat, and when.

“In recent years, changeable weather patterns have emphasised how variable the liver fluke challenge is, both in terms of its extent and timing, and 2025-26 is following this trend,” says John Graham-Brown of NADIS and the University of Liverpool.

“For several years now, the fluke challenge has been lower and later than traditionally expected in many parts of the country. However, many farmers are sticking with traditional treatment windows, meaning a large proportion of treatments are being given too early. This leaves livestock susceptible to disease, as the challenge typically increases through the autumn and into winter. There is no ‘insurance’ element associated with a fluke treatment given too soon,” he adds.

“In Scotland, we are also seeing a much later start to the liver fluke season.” says SRUC Vet, Heather Stevenson. “Last year, it was late in the autumn before we saw significant evidence of disease, even in some of our very high-risk areas. This is a long time after many traditional treatments had been given.”

Rebecca Mearns of APHA agrees: “Our data also shows the trend towards much later liver fluke infections. We even had reports of acute disease due to immature fluke parasites in sheep in late winter / early spring in 2025. Farmers are often surprised that they have liver fluke issues because they treated stock earlier in the autumn. The problem is that flukicides have no residual effect (or persistency), so if they put the stock back on to ‘flukey’ areas after treatment, they are as just as susceptible to a later challenge as untreated stock.”

What can farmers do?

“The key to deciding whether to treat and when, is to test,” says Philip Skuce of Moredun, “and the first line of defence would be tests in the late summer and autumn that can detect early infection, from as little as two weeks after fluke are ingested off pasture.*

“This involves either a blood test, or the new Lateral Flow Test (LFT), which is carried out on-farm. Both methods detect circulating antibodies to liver fluke and when used on this year’s first season grazing animals (lambs or calves), these animals can be used as ‘sentinels’ to identify if liver fluke is present in different management groups and/or parts of the farm. By repeating the test every 3-4 weeks until either it is positive, or faecal methods can supersede this test, this can also answer ‘when’ to treat, avoiding unnecessary and costly treatments that are too early.

“Consideration also needs to be given to which flukicide would be most appropriate to use, given the likely age of liver fluke infection and age kill of the respective flukicides, and informed by testing.”

“The need to use testing to see if, and when, liver fluke is a threat, has never been more important,” adds Lesley Stubbings of SCOPS. “To help farmers and their advisers to adopt antibody testing early in the season, we have recently released a podcast on the subject, which sits alongside the other advice on the SCOPS and COWS websites, together with podcasts on liver fluke in general from previous seasons.”

For further information on liver fluke and a link to the SCOPS podcast series click here.