Diagnose and treat dairy cows for fluke before turnout

Dairy farmers are being advised to treat cows infected with liver fluke before turnout to reduce pasture contamination.

At this time of year, animals have been housed for three to four months so only adult fluke should be present in the cattle, explains vet adviser for MSD Animal Health Matt Haslam. “Treatment now with oxyclozanide will kill adult fluke in the bile ducts and prevent them laying eggs that will contaminate pasture,” he says.

To diagnose whether liver fluke is a problem, Mr Haslam says a bulk milk test is a good starting point.

See also what products can be used to treat fluke

“The result will tell you if your herd has been exposed to liver fluke. If the result is negative, you still need to remain vigilant – particularly if your farm is wet – but if it is positive, your vet will need to carry out further investigation. This may involve taking faecal samples for analysis or even blood sampling any thin or scouring animals,” he says.

Treatment time

Westpoint senior vet Jon Parsons says farmers should treat infected cattle three to four weeks before turnout to ensure adult egg-laying fluke are destroyed.

Signs of chronic fluke

  • Lower body condition score
  • Reduced milk yield
  • Poor-quality colostrum
  • Bottle jaw

“As fluke eggs can be shed up to three weeks after treatment, the best plan is to treat now as most herds won’t be turned out until the end of March or early April. This gives any eggs a chance to be deposited inside and lower pasture contamination,” says Mr Parsons.

While use of a product containing albendazole may seem like a good option to control fluke egg shedding, unless worms are also a problem, this should be avoided to prevent worm resistance.

Mr Parsons advises any groups – for example, dry cows or heifers – kept or grazed separately to be screened independently, due to the different treatment options for fluke depending on its stage of development.

Due to the long period between ingestion of the parasite to its development into an adult laying eggs (two to three months), faecal egg count tests may come back as negative, even when the herd or pasture is considered high risk, says Mr Parsons. In this case, further testing should be considered in the future as animals may then test positive.

Pasture management

As temperatures reach about 10C, the larger numbers of host snails will begin developing and shedding infective fluke stages – a process that takes about six to seven weeks.

In addition to higher numbers of host snails, a lack of frosts over winter means all remaining infective stages that weren’t ingested the previous autumn won’t have been killed off. This is a more immediate risk, though most of these die off by midsummer.

“Pasture management is going to be key this year in terms of fluke control. Farmers turning out should be aware of potential infection from now,” Mr Parsons adds.

“Moving creep feeders, ring feeders and troughs in fields regularly will ensure areas do not get heavily poached and cow tracks should be carefully managed through the spring to maintain good gateway and track conditions,” he says.

Dairy treatment options

Drug name

Can be used in

Active against

Restrictions

Triclabendazole 24% (240 mg/ml)

Dry cows and pregnant heifers

Fluke aged two weeks or more

Must be given 48 days before calving. If calving occurs sooner, milk still can’t enter the bulk tank until 50 days post-treatment (48 daysplus 48-hour standard withdrawal post-calving)

Oxyclozanide 3.4% (34mg/ml)

All cows and heifers

Adult fluke

Milk withdrawal of 72 hours

Albendazole 2.5% (25 mg/ml) and 10% (100 mg/ml)

All cows and heifers

Fluke aged 10 weeks or more, fluke eggs, roundworm, lungworm and tapeworm

Milk withdrawal of 60 hours