Successive dry periods during the summer of 2018 and the two springs in and 2019 and 2020, coupled with some extremely wet weather at the end of last year, have resulted a surge in liver fluke in all parts of the country.

Such has been increased evidence of this parasitic worm, that a new report from the Sustainable Control of Parasites in Sheep (SCOPS) and Control of Cattle Parasites Sustainably (COWS) groups, is warning all livestock farmers to be on their guard and use the tests available to monitor the situation on their farm.

The two industry led groups point out that increased levels and new infection of fluke are being seen in many parts of the country.

Sub-acute cases in sheep, caused by migrating immature fluke, have been reported in North West England, and APHA has identified cases in the Midlands and Cumbria too.

Positive fluke egg counts are also starting to be seen in the West of Scotland, indicative of the presence of adult fluke.

However, while increased evidence of the parasite is being seen, testing is key to prevent product resistance.

As an example, the University of Liverpool has tested first season grazing lambs and calves from across the country and seen significant regional variation.

Even within a county there are differences between individual farms. And while farms from Wiltshire, North Yorkshire and Northampton have tested negative, farms from East Sussex and Exeter were positive. Therefore, testing before treatment is paramount.

There are also reports of coproantigen positives from Cheshire, the North of England and Scottish Borders. Different results can be seen in different groups of animals grazed on different parts of the farm, again highlighting the need to test before treating.

How to test/options available

In the autumn fluke update, SCOPS and COWS advocated the use of serological i.e. blood testing to monitor infection in lambs and calves, because they were in their first grazing season and, therefore, good sentinels for infection.

At this time of the year (mid-winter), most of the fluke are adults so the preferred option is testing of faeces using either the fluke egg count or the coproantigen test. These tests can be applied to any age or management group of sheep and cattle and are relatively straightforward samples to collect.

Faecal testing from late autumn through to spring will tell farmers whether or not treatment is needed, and help guide the timing of treatment and product choice. It also provides an opportunity to see how well any treatment has worked with follow-up testing.

For animals kept outdoors, regular testing is best – it helps monitor the reinfection rate and can be a good indicator if re-treatment is necessary. For housed animals a single test before turnout identifies any ‘leftovers’ from housing treatment.

Case study – Argyll, West of Scotland (Moredun and Livestock Health Scotland). This is a notoriously wet and mild part of the country so fluke is a perennial problem. Over the years, farmers have routinely treated with triclabendazole (TCBZ) in the autumn (and at other times) resulting in widespread TCBZ resistance.

Regular faecal monitoring on Livestock Health Scotland study farms over the past few years has avoided use of TCBZ in autumn (or the need to treat at all, in some cases) and delay treatment with alternative products (closantel and/or nitroxinil) until well into the New Year.

Brian, an Argyll farmer involved in the work, says: “Having been involved in sampling for the trial for the last three years, I’ve been able to better target when I dose stock for fluke, resulting in money and time being saved from less routine dosing, and I now have a healthier flock.”

His vet, Alison, says: “Timing of fluke treatments in the face of suspected or proven TCBZ resistance continues to challenge mid-Argyll farmers and vets.”


If results come back positive, discuss with your veterinarian or RAMA which product to choose for treatment. The SCOPS/COWS treatment table can help to select the right treatment and optimise timing.

For sheep

Most fluke found in outdoor sheep situations will be late immature and/or adults, so a product targeting these stages (closantel or nitroxinil) is advised. Later in the spring, products targeting adult fluke could be used (albendazole or oxyclozanide). Avoid turning sheep out onto ‘fluky’ pasture once treated, to prevent re-infection.

For cattle

Assuming cattle were housed in October, most fluke will now be adults. A faecal egg count or the coproantigen test could be used. A product targeting adult fluke such as clorsulon or oxyclozanide can be prescribed. Treatments given early after housing are likely to miss some immature fluke.

By spring and turn-out, these will be adults and producing eggs. Test in the spring using either the faecal egg count or coproantigen test to show if stock are still infected. Following a positive test, a pre-turnout treatment with a product targeting adult fluke (clorsulon, oxyclozanide or albendazole) will reduce pasture contamination with fluke eggs in the spring, just as the mud snails are becoming active again.

Always be aware of the withdrawal periods for meat and milk for any treatments given – see SCOPS/COWS guidance.

Action points

Test before you treat – testing stock before treating will indicate if treatment is necessary this season, the most effective time to treat your stock depending on the fluke challenge for your farm, and help inform product choice.

Faecal test sheep and cattle (FEC or coproantigen) to monitor fluke infection status, and re-test same animals three weeks post-treatment to check efficacy.

Test cattle two months after housing to help detect infection in older cattle or farms with a low fluke risk.

Speak to your vet about which tests are available and to arrange testing.

If test results are positive, treat with a product that targets the stage of fluke most likely to be present at this time.

By testing before treatment, the correct product can be selected to treat the right animals at the right time to give effective and efficient fluke control.