Managing Liver Fluke in Dairy Cows

Effectively managing fluke infections in dairy cows is inherently difficult because of the limited number of actives available and the limited opportunities to treat cows without discarding milk.

What is the impact of liver fluke in dairy cows?

The impact of liver fluke on any animal is hugely variable depending entirely on the number of fluke ingested. However, studies have shown affected animals can suffer:

• a reduction in milk yield by 3.8%-15% ⁽¹⁾
• reduced butterfat and protein percentage ⁽²⁾
• reduced feed conversion efficiency and dry matter intake ⁽³⁾
• reduced fertility ⁽¹⁾

Unlike gastrointestinal worms cattle do not develop immunity to liver fluke, therefore any dairy animal grazing pastures with mud snail habitats from August onwards is potentially at risk of fluke infection. See COWS website here for more information on when infectious stages of fluke are likely to be present.

Once liver fluke are in the liver they can survive there for months and in many cases years unless an effective treatment is given. Find out more about liver fluke here

Licensed treatment options for adult dairy cows

*guide only - individual products vary. Check SPC/datasheet for specifics

What can we treat and when?

Managing fluke takes thought and forward planning to minimise the impact of fluke on the dairy herd while ensuring compliance with milk withdrawal periods:

"My cows are in milk, what can I use?"

• For adult cows the best option on most farms is to control fluke at drying off to avoid any milk discard. No flukicides have persistent activity so will only remove the fluke that are present (and only the stages the actives kill) at the time of treatment.
• The only flukicides with a milk withhold and that can be used during lactation are albendazole and oxyclozanide. These will target the adult fluke over 10 weeks of age- fluke younger than this will be left behind, therefore if there is very heavy infection repeat treatment may be required (or utilise control in the dry period and through grazing management etc).
• Fluke antibody testing may give an idea of exposure. Also cull cow slaughterhouse data is invaluable.

"My cows are dry what can I use?"

At dry off there are further options.

• In the spring and summer it is hoped (depending on your farm situation and topography) that the risk of picking up immature fluke is low, therefore the active of choice should be to target the adults, i.e. either oxyclozanide or albendazole or clorsulon (in combination with ivermectin) if worming required too.
• In the autumn and winter where the animals in question have been grazing areas containing snail habitats they are likely to have picked up immature fluke, therefore the best option here is to give an active that will target from the immatures stages, i.e. triclabendazole oral drench. This will target down to fluke of 2weeks of age.
• It must be remembered that if they continue to graze the high-risk pasture after being drenched they could become re-infected and still enter the herd with fluke infection.

"I have pregnant heifers – what can I use?"

Other actives can be used in heifers but not after the second trimester of pregnancy as there is no maximum limit set for these actives in milk. as explained on the COWS website.

“What about my young stock?”

It is important to note that certain actives are NOT permitted for use in cattle of any age intended to produce milk for human consumption. These include triclabendazole in combination with moxidectin, or oxyclozanide in combination with levamisole.

Actives that could be used in young stock include some closantel or nitroxynil products; please check SPCs for details. See here for more details.

“I have sheep in for sheep keep over the winter - does this affect my fluke risk?“

It certainly could, depending on

• their management
• the risk of land they have come from
• the land they are coming on to.

See why the fluke risk varies here

Treating animals is only one part of an effective liver fluke control plan. The Four Point Plan is the best approach for effective liver fluke control.

Eamon Watson MRCVS, Veterinary Advisor at National Milk Laboratories comments on testing for medicine residues:

“Testing for residues isn’t about catching people out, it’s about assuring the milk supply chain and testing is a central part of this. The testing for medicine residues, including flukicides, has taken a step forward. New technology means it’s now relatively simple to screen bulk milk samples for the range of worm, fluke and other endectocide products. National Milk Laboratories have been using this testing technology for some time to help milk buyers and vets investigate bulk tank fails from antibiotic residues in milk samples and are currently validating a new test for use to detect residues from injectable, pour-on and oral parasiticide products.

Testing for flukicides isn’t new – but testing for a broad range of medicines is now much easier. It is worth highlighting that awareness around medicine residues has always been a vital part of ensuring food products are of the highest quality. This all starts with the correct selection and use of products to minimise the risk of residues in milk from treated cows.”