While the risk of liver fluke remains low for much of the UK this season, livestock farmers need to keep their guard up again in what is becoming a less predictable parasite challenge. That is the warning from the Sustainable Control of Parasites in Sheep (SCOPS) and Control of Cattle Parasites Sustainably (COWS) groups as we head into winter.
Experts from the two groups say this unpredictability means diagnostic testing is critical to make sure animals aren’t treated too soon, or unnecessarily, or miss a vital treatment.
John Graham Brown of Liverpool University, speaking on behalf of both groups, said: “It is really important to repeat testing until the risk period is over.
“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. Sheep are most likely to be seriously affected by acute liver fluke disease in the autumn and early winter, which means they are the priority for testing and also the best indicator of the presence of liver fluke on the farm.”
Matt Colston, a vet with Elanco Animal Health, said the recent change in weather, becoming wet and relatively mild in some areas, will favour the mud snail that is critical to the liver fluke lifecycle.
He said: “This means we could see an increase in infection rates in the coming weeks. The mild weather has also meant that cattle have tended to stay out longer, potentially exposing them to more risk.”
Rebecca Mearns, president of the Sheep Veterinary Society and Biobest’s senior veterinary advisor, said: “So far this season we have seen positive results in tests on faeces in some areas, though many samples received have tested negative as the liver fluke stages in the cattle and sheep are not yet mature enough to be detected by these tests.
“I would also urge livestock farmers to take note of feedback on liver rejections from the abattoir and always investigate any deaths with a post-mortem examination to check for evidence of fluke in the liver.”
SCOPS and COWS urge farmers, vets and advisors to note that the withdrawal of Trodax from the market means there are now only four actives available for sheep, and two of those are only adulticides (i.e. they only kill adult fluke).
There are five actives in cattle, three of which are adulticides. However, there are flukicides with nitroxynil as the active ingredient available outside the UK and it is possible to import these under a Special Import Certificate (SIC) submitted by a veterinary surgeon to the VMD.
Lesley Stubbings of SCOPS added: “It can be a challenge to choose the right product, given the range of trade names and names of actives, difficulties getting hold of some items, and the added complexity of combination products. But use the expertise of your vet or adviser and make the right choice for you flock or herd.”