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Sheep farmers urged not to do get caught out by ‘low’ fluke risk this winter

Sustainable Control of Parasites in Sheep (SCOPS) and Control of Cattle Parasites Sustainably (COWS)
 
While liver fluke burdens on pasture have generally been lower than last season, experts are warning it is dangerous to assume this applies to all farms, all areas on a farm, or that levels will remain low as the autumn and winter progresses.
 
Speaking on behalf of the Sustainable Control of Parasites in Sheep (SCOPS) Group, Lesley Stubbing says: “Reports from around the UK generally suggest we have not yet seen a major challenge from liver fluke – but there are a few individual cases, so it is essential to keep monitoring. Worms remain a major issue on many sheep farms, including evidence of resistance, so we must keep testing and not assume that because it is winter the threat from worms has gone away.”
 
SCOPS provides this top tips for sheep farmers:-

  • Don’t get caught out by treating too early. Many sheep farmers treat for fluke too early in the autumn and assume this will provide sufficient cover for their flocks. This is unlikely to be the case. Monitoring is essential to determining the need and timing of further treatments.
  • Worms can produce similar signs to liver fluke disease. This has caught some farmers out this autumn, including in ewes which can be affected by the Haemonchus contortus (or Barber’s Pole) worm.
  • Investigate deaths. A post mortem is still the gold standard to establish whether fluke is present, so consider further action with deadstock.
  • Monitor abattoir returns carefully. These are valuable reports regarding the presence of liver fluke.
  • In lower risk situations, consider treating sheep with closantel or nitroxinil. This will take the pressure off triclabendazole, to which resistance is building. Seek advice from your vet or animal health advisor on product choice.

Updates from around the UK

  • Diana Williams, Liverpool Veterinary Parasitology Diagnostics, Liverpool University: “We have conducted egg counts on sheep and beef farms in North Wales and North West England over the past two months. Most beef herds and sheep flocks have had low liver fluke counts, but some sheep flocks had very high counts. They were investigated using a faecal egg count reduction test and found to have high levels of resistance to triclabendazole. My overriding message would be to test before you treat.”
  • Rebecca Mearns, Biobest: “We are receiving a lot of faecal samples for testing for fluke eggs and the fluke feeding antigen (coproantigen test) and many are also examined for worm eggs. There is still little evidence of liver fluke on faecal testing, though we have had some high positive blood antibody levels in first season grazing cattle, so liver fluke is clearly still out there. In lambs we are also still seeing some very high worm egg counts, and this seems to be a major problem leading to poor performance and ill thrift right now.
  • Philip Skuce, Moredun, on monitoring work in Argyll: “We are continuing to sample in Argyll but there has been little change since mid-September when we started with low egg counts of both liver fluke and rumen fluke on most farms. In a year when the situation is very different, I understand it is difficult for farmers to hold back on treatment for fear they may get caught out. However, they need to try and avoid unnecessary early treatment, which could lead to a false feeling of security. Careful, continued monitoring is vital.”
  • Ben Strugnell, Farm Post Mortems Ltd, County Durham: “I have seen a lot of parasitic gastroenteritis (PGE) in lamb sent for post mortem, including haemonchosis, which may be the most likely reason for poor performance (rather than fluke) in North East England. Several cases have revealed unequivocal evidence of anthelmintic resistance to white (1-BZ) and clear (3-ML) drenches so the opportunity to assess anthelmintic efficacy should not be missed if dosing. I have still not seen any acute fluke in sheep but wetter weather in the coming weeks will surely bring some.”
  • Heather Stevenson, SRUC Veterinary Services, based in Dumfriesshire: “We have not seen any cases of sudden death due to acute liver fluke so far this autumn. Losses in lambs have mainly been a result of high worm burdens and/or pasteurellosis.”
  • Sian Mitchell, APHA, based in Carmarthen: “We are detecting fluke eggs in faeces or liver damage due to fluke on post mortem examination, suggesting chronic fluke infections, but no diagnoses of acute fluke as yet. Severe roundworm infections in lambs is still a major concern so sheep farmers need to get a diagnosis as to cause of diarrhoea or death.”
  • Lesley Stubbings, SCOPS: “It is vital to keep a careful check on individual farms. We have been advising against treating without having evidence of the need so far this winter, but we know many farmers have treated anyway because they are nervous of acute liver fluke disease. These farmers must remember this will not protect them should the challenge increase in the next few weeks. Flukicides have no residual effect, so their animals are at the same risk as those on farms that have not treated yet should things change.”

More at www.scops.org.uk and www.cattleparasites.org.uk.
 

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