Expert advice for county Longford farmers to prevent river fluke in sheep

High rainfall in county Longford and the Midlands in the last two months has provided the optimum environment for the mud snail and hence is likely to lead to high incidences of liver fluke disease late this year and early 2026.

This is now evident in the last month with slaughterhouses reporting an increase in its prevalence particularly for sheep out on pasture during that time.

Disease
Liver fluke is caused by a flat leaf-like worm called Fasciola Hepatica.

The fluke cycle involves two separate hosts, the mud snail and the sheep. The risk of liver fluke disease is closely linked with summer/autumn rainfall and if left untreated can result in the death of sheep.
 
It is vitally important that farmers can spot signs of the disease as early as possible so treatments can be started without delay. Disease in sheep is caused when the flukes travel through the animal’s body and burrow into the liver tissues.
In sheep liver fluke disease can have three stages with following symptoms;

Acute- Leads to sudden death
Subacute- Rapid weight loss leading to a reduced physical condition in sheep (usually in Winter months)
Chronic - This causes long term weight loss. Signs include poor body condition and bottle jaw

Treatment
Drenches can be divided into a number of groups according to active ingredient, although the choice of product should be based on the stage of development of the fluke.

Triclabendazole; only group that has activity against early immature fluke Closantel, Nitroxynil, and Rafoxanide; active against immature fluke over six weeks old

Oxyclozanide and Albendazole; are only active against adult fluke.
The greatest threat is likely to be from immature fluke, particularly for sheep out on pasture at this time.

If a large presence of immature fluke is detected, a product effective against immature stages should be used provided there is no history of resistant to these products.

If there is a history of liver fluke on your farm and suspected resistance to fluke drenches is present, a more effective control program should be implemented in conjugation with your veterinary surgeon.

When animals are to be slaughtered it is critical to be aware of withdrawal periods.

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