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Liver Fluke



  • Fasciola hepatica

  • Affects sheep, cattle, horses and donkeys

  • Causes severe symptoms in cattle and sheep. Generally, horses have resistance towards the parasite and when infected symptoms are usually mild. Cases are more common in younger horses before immunity has developed.

  • The snail, Lymnea truncatula, is an intermediate host

  • More common in the wetter, western areas of Britain and a particular problem in places where there is wet or poorly drained land i.e. next to a river




Adult liver flukes live in the bile ducts in the liver of a mammalian host. Here they lay a large number of eggs which are excreted in faeces. At temperatures of 10oC and above these eggs develop and hatch within 2-4 weeks. In wet conditions the larvae swim to penetrate the water snail, Lymnea truncatula, which acts as an intermediate host. Here, the larval stage develops and multiplies over the next 6-8 weeks. When released from the snail, larvae develop into infective cysts which are found on plants and ingested by mammals. These cysts can survive for up to one year in optimum conditions if there is no frost or dry periods. After ingestion, fluke hatch in the small intestine and migrate across the gut wall to the liver.























What do they look like?


Grey/brown leaf shaped parasite, 2-3cm in length















What damage can they cause? 


  • Sharp spines irritate the liver

  • Found in the bile ducts where they cause thickening of the walls and liver damage


Clinical Signs


  • Due to the lifecycle of the snail disease is normally seen autumn/early winter

  • Causes more severe symptoms in sheep and cattle, usually mild symptoms in horses

  • Anaemia

  • Oedema

  • Weight loss

  • Diarrhoea

  • Colic


Diagnosis and Detection


  • Cannot be detected through normal faecal egg counts

  • ScientifEQ offers a faecal liver fluke test for horses and sheep. This test assesses dung samples for the presence of fluke eggs



















  • There are currently no liver fluke treatments licensed for use in horses

  • Chemicals used to treat sheep and cattle can be harmful to horses


Preventative Measures


  • Occurrence can be reduced by not grazing animals on wet or poorly drained land.

  • The exclusion of the snail habitats from livestock grazing areas will offer some protection, drainage eliminates the snail.


Current Issues in 2015


  • Patterns of emergence changing possibly due to climatic changes

  • Now widespread across the UK and increasing in frequency

  • More prevalent in the wetter, Western areas of the country but there has been evidence of an increase of cases in Eastern regions.





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