Killing liver fluke: ‘When should I use this product so that it is most effective?’

Niall Treanor, B& T Drystock Adviser, Teagasc, Galway/Clare, discusses liver fluke in this article.

Coming into the autumn, dairy and beef farmers can be sure of the certainty of having liver fluke in their stock coming to this time of the year.

Due to the dry weather conditions in many parts of the country this summer, there is a moderate risk of liver fluke-related disease this winter for the north, west, south-west and midlands.

A lower disease risk is expected for the east and parts of the south. However, farmers in these lower-risk areas should remain vigilant for signs of disease.

Liver fluke cycle

The liver fluke parasite, Fasciola hepatica, is a parasite that affects cattle, sheep, and goats. Adult fluke in the bile ducts lay eggs that pass on to the pasture in the faeces.

The eggs require mild conditions for the larvae to hatch. After some time, these enter the intermediate host, the mud snail, where they undergo further development.

This snail is even more dependent on the presence of moisture and warmth.

The immature flukes leave the snail and develop further until they reach the ineffective stage, where they become attached to the herbage.

It is only when ingested by the animal at this stage that they can migrate through the body, reaching the liver and thus completing the cycle.

Products for killing liver fluke

There are many products effective at killing them. Farmers are aware of the parasites for decades, and most treat their cattle at housing for them.

However, every year we still see a high percentage of livers in meat processing factories from housed cattle that have live adult liver fluke in them.

Why is this? There are several possible reasons, including:

• Using a control product that only kills a proportion of the fluke in the animal;
• Underestimating the animal’s weight;
• Not giving enough product;
• Incorrect treatment procedure;
• Using a product that the fluke are resistant to.

Products to kill liver fluke

When purchasing a product to kill liver fluke, the most important question to ask is: “When should I use this product so that it is most effective”?

Most of the flukicides for sale only control older immature liver flukes and/or adult fluke. This means that any fluke that has been picked up over the previous six to eight weeks or so will not be killed. A second treatment for fluke will then be necessary.

Triclabendazole-based products will kill much younger fluke, but there are reports that resistance to them appears quite widespread in Ireland.

Dung sampling 

To be sure that a fluke control programme has worked, it is a good idea to send off dung samples for testing eight weeks after you have given the last treatment.

Only then will you know for certain whether or not it has been effective.

Now is the time to implement a dosing plan in partnership with your vet to effectively control fluke in your herd.

Choose your product carefully, administer it correctly and check dung samples to know for certain if the job is done.

More technical advice and farming tips.