Persistent liver fluke risk for cattle and sheep despite cold snaps

This means livestock farmers must not drop their guard, warn experts in the Sustainable Control of Parasites in Sheep (SCOPS) and Control of Cattle Parasites Sustainably (COWS) groups.

Philip Skuce of Moredun sits on both groups. He says: “Testing is critical to make sure farmers don’t treat too soon, or unnecessarily, or get caught out and miss a vital treatment. The cold snap in December will not have killed off all the liver fluke on pasture, so animals could still be picking up infection that could go on to cause disease. Livestock farmers must continue to test if they are to ensure any treatment is both necessary and given at the right time and with the most appropriate product.”

Diagnostic reports from the Animal Plant and Health Agency (APHA) and Scotland’s Rural College (SRUC) underline the value of using blood testing for fluke in sentinel lambs or calves.

Heather Stevenson, a vet with SRUC, explains: “In September and October, less than 1% of the animals tested were positive, showing the majority of farms did not need to treat at that stage. This rose to 10% by mid-November and 13% in December, which is still a small proportion of farms and highlights the potential to treat unnecessarily or too early if traditional timings are followed.

“In January, 30% of samples tested for coproantigen (a faecal test) were positive, which underlines the need to keep checking sheep that have not yet been treated.”

John Graham-Brown from the University of Liverpool stresses how important it is to repeat testing until the risk period is over. He says: “A negative test does not mean you can sit back and relax. Plan to repeat tests in three to four weeks’ time to make sure you don’t get caught out.”

This is echoed by Rebecca Mearns, vice president of the Sheep Veterinary Society and vet with Biobest. She says: “We are seeing some faecal samples that are positive for fluke eggs this winter, but with infections tending to be later, farmers must not assume one negative test means there are no liver fluke, it may be because the fluke are not mature enough to lay eggs.”

Now is a good time for housed cattle to be tested for fluke, using a composite dung test to check for fluke eggs. If cattle are positive, choosing a treatment that targets adult fluke and avoiding products containing triclabendazole, will reduce resistance selection pressures on the parasite. Reducing eggs going onto pasture in the spring can help reduce challenge this coming autumn.

Remember:

• Ewe lambs or retained store lambs can still be blood tested to monitor liver fluke infection.
• A negative test does not mean you can sit back and relax. Retest every 3-4 weeks.
• Investigating unexpected deaths via a post-mortem remains a key means of establishing whether or not liver fluke is present in the flock/herd.
• If you have already treated for liver fluke but the animals remained at grass, they are at risk of reinfection. Make sure you test using faecal samples.
• Now is a good time to test housed beef cattle (once they have been inside for 10-12 weeks),  before they go back out onto pasture. Check for eggs in dung or use a copro-antigen test.
• Faecal testing for liver fluke eggs only detects the presence of adult fluke, not immatures, so you may need to re-sample
• Abattoir feedback is a really valuable source of information with regard to liver fluke infection.
• Talk to your vet or adviser to discuss whether any treatment is necessary and which product (active) to use.

More information for cattle at www.cattleparasites.org.uk and for sheep at www.scops.org.uk.