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Liver Fluke Control in Sheep

Liver fluke has spread over the last decade and is now found across the country. This is due to:

  • Greater movement of infected animals
  • Inadequate (or sub-optimal) quarantine treatments
  • Changing weather patterns – increased rainfall and milder winters

Liver fluke has 3 stages in the animal – early immature, immature and adult – all of which cause liver damage and decrease feed intakes and efficiency of utilisation.2 The objective of liver fluke control is to reduce the risk of infection to a level that does not impact on animal welfare or affect the efficiency or economics of production.



Controlling the right stages of liver fluke, at the right time, with the right product:

Seasonal, strategic liver fluke treatments can help reduce the risk of resistance developing and the levels of infective cysts (Metacercaria) on pastures. As not all active ingredients kill all stages of liver fluke, knowing which active ingredient kills which stages is important to ensure you choose the correct product for the stages of fluke likely to be present.


Liver Fluke Timing

To avoid overuse of any single active and to reduce the risk of resistance development, targeting the right stages of liver fluke at the right time of year with the right product is essential.The suggested treatment timings are for guidance only. Levels of risk in your area, or on your farm, can be determined by consulting with a local animal health adviser or veterinary surgeon and checking current liver fluke forecast data.

Sheep Liver Fluke

Always check individual product SPCs and seek advice from vet or animal health provider.


Resistance to triclabenadzole has been identified on a number of farms. To identify resistance problems early, it is recommended to check that treatments have been effective. Once liver fluke have become resistant to an active ingredient, and can survive exposure to a treatment that would normally kill them, there is no evidence to suggest they will return to susceptibility.

As individuals, and as an industry, we can’t afford to allow this to happen. To achieve effective control now – and to preserve the efficacy of the existing active ingredients for the future – we need to adopt a new approach to liver fluke management.

This can be achieved by concentrating on the 4 key elements for sustainable liver fluke control


Always follow the SCOPS guidelines on quarantine treatment and give bought-in stock a quarantine flukicide dose.

  • Whilst treatment with triclabendazole will remove a very high proportion of susceptible liver fluke of all stages it will not remove triclabendazole resistant liver fluke.
  • If sheep are infected with early immature liver fluke, treatment wilth closantel will have to be repeated after the immatures are old enough to be killed by these products. Consider the use of two doses of closantel given 6 weeks apart.
  • Treatment with more than one product with activity against immature liver fluke (closantel or triclabendazole) will reduce the risk of introducing liver fluke with resistance to any one product. However, it is not recommended that two products are used at the same time, (seek advice from an animal health adviser or veterinary surgeon).
  • Keep treated animals away from snail habitats (wet, boggy areas) for 3 weeks as treated sheep can still shed eggs for up to 3 weeks.

Coproantigen testing and Feacal Egg Count (FEC) monitoring can be used to determine the need for further treatments.


Even when the fluke forecast is low risk, this does not mean there is no risk. The fluke risk depends on the habitat on the individual farm, and on some farms in a dry season when the regional risk is low, the available grazing will be concentrated in the wetter areas of the farm where fluke will still be present.

Even low levels of fluke which don’t cause obvious clinical disease, will still have a significant impact on animal health and productivity. Don’t get caught out, when the forecast is for low risk, make sure you investigate the fluke challenge on your own farm.


See the current liver fluke risk forecast from NADIS here.



PM-UK-19-0844