October 2026 – Tackle Liver Fluke: Plan Your Control Before Housing

The mud snail is the core of the fluke life cycle, being used as an intermediate host. The snail itself thrives in wet weather in spring and summer, reproducing quickly and being available as a host for the fluke. Fluke eggs hatch in warm, wet weather and these hatchlings then infect snails, where they multiply. Once the fluke are shed from the snail, they can infect grazing cattle. This usually happens from autumn to winter, but animals can be infected early in the spring season by liver fluke that overwinter in the snails or on the grass.

Liver fluke thrives in mild, wet weather, making the northwest of Ireland particularly suitable for them but can be a threat for the whole country. During autumn, try to avoid grazing heavy ground that becomes waterlogged or floods during the year.

In cattle and sheep, liver fluke infections can cause:

• Reduced milk yields
• Reduced growth rate
• Decrease in immunity leaving them susceptible to other diseases
• Poor feed conversion
• Death in sheep

Sheep are generally more susceptible to severe disease, with acute infections causing anaemia and death typically in the autumn. In cattle, there aren’t always clinical signs but the loss in production and growth rates can mean later finishing or lighter carcasses.

Signs to look for, particularly in sheep:

• Pale mucous membranes
• Rapid weight loss
• Lethargic animals
• Bottle jaw
• Scour
• Death

Diagnosing liver fluke

Diagnosis can be confirmed through dung testing, faecal egg counts (FECs) or coproantigen tests, and blood or milk ELISA testing routinely done on bulk milk. FECs cannot detect immature liver fluke infections. Immature fluke cause the most damage in sheep, therefore clinical signs and farm history need to be considered. If you wish to check whether liver fluke is present on the farm, FEC testing done in late winter is usually the best time to detect eggs, or the Beef HealthCheck reports from the factories can show if liver fluke was seen on the liver in finishing or culled cattle.

Different drugs are effective against differing stages of liver fluke infection. It is important to select a product with the appropriate active compound given the time of year and stage of infection that requires treatment. If treating at housing, remember it’s not uncommon for animals to pick up new infections throughout autumn up until they go into the shed. This means they may have different stages of liver fluke present. If using a flukicide soon after housing that is only effective against the adult fluke, it’s worth checking 6-10 weeks later if re-treatment is needed by faecal sampling. Alternatively, if the risk is not very high, treatment can be delayed by 6-10 weeks depending on the product used. Triclabendazole is the only active ingredient effective against all immature and adult stages of liver fluke. However, resistance has been reported in Ireland, making responsible treatment use essential. Ideally, these products should be kept for severe disease. Speak to your veterinarian for advice on treatments.