Delay fluke treatment to maximise effectiveness

Farmers are being urged to speak to their vet or suitably qualified person (SQP) to get the correct flukicide for effective treatment of liver fluke this autumn.


The warning comes after changes to flukicide treatment of lactating animals have made it increasingly confusing for dairy producers.


Speaking to Farmers Weekly vet Fiona Anderson, from Novartis, says it is crucial farmers treat liver fluke with the correct active ingredient to ensure it targets the correct stage of its life cycle and to prevent drug resistance.


“Although levels of fluke are definitely lower this year thanks to the drier summer, there is a medium risk and we are starting to see livers being condemned,” she says.


Host snails need water and warmth to encourage them on to ground level where they deposit their cysts. Some parts of the country have seen higher rainfall for the last six to eight weeks, which means they could be at a higher risk.


The snails will hibernate in temperatures of 10C or lower, so no new cysts should be produced and existing ones should die off over the winter. However, farmers should remain on their guard in case of a mild winter, she says.


Beef


Miss Anderson explains that while fluke infections are never black and white, at this time of year fluke in their early stages are generally more prevalent. Once correctly diagnosed, a product targeting the immature stage can be used.


Immature fluke cannot be killed until they’re at least two-weeks-old, using a product containing triclobendazole, so cattle should not be treated at the point of housing. A delay before treating is vital to maximise treatment effectiveness and ensure that any fluke cysts that have been ingested immediately before housing have time to mature.


“It is good practice to wait the appropriate length of time after housing, depending on the product being used; this can vary from two to 10 weeks after infection,” says Miss Anderson.


Dairy


Since changes to the use of flukicides in dairy cattle, farmers have a much smaller product selection. When lactating cows are sick there are only two active ingredients suitable; albendazole is a fluke and worm treatment, with a 60-hour milk withdrawal time, whereas oxyclozanide is a specific flukicide that has a 72-hour milk withdrawal period.


But both of these only treat adult fluke. Triclabendazole 24% can treat immature stages, but can only be used in dry cows more than 48 days from calving.


Matt Haslam, ruminant veterinary advisor for MSD Animal Health advises dairy farmers to plan their treatment and the first port of call should be taking samples to assess fluke levels.


“A bulk milk test is easiest and will tell you if the herd has been exposed. If it is negative, farmers need to remain on their guard, but when it is positive they can go on to take faecal samples for further testing or ask their vet to blood sample thin or scouring animals,” says Mr Haslam.


Once animals have housed for 10 weeks, a flukicide that kills adult stage fluke will result in less pasture contamination post turn out. “At this point, there would only be adult fluke present, which could be treated before turn out in the spring to kill all adult fluke and prevent eggs being shed onto pasture,” he says.


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For more information on the use of flukicides in beef cattle, go to www.cattleparasites.org.uk

For more information on changes to the use of flukicides in dairy cows throughout their production cycle, go to www.defra.gov.uk

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