The latest results from a national fluke surveillance study have restated the need to monitor for fluke infection on a case-by-case basis, after two farms in close proximity were found to have a different fluke status.
Astudy undertaken by XLVets and 30 of its member practices has seen a vet from each send blood samples for analysis from lambs on farms with a history of liver fluke.
Amour Vets in Ayrshire has two farms participating in the study. Alan Walker, a vet at the practice, explains their results had shown lambs on one of these farms had experienced exposure to fluke, with samples from the second remaining clear despite the close proximity of the two holdings.
Mr Walker says: “Fluke is a big challenge in the region due to the combination of high rainfall and heavy clay soils.
“Historically, faeces samples have shown fluke eggs to be present in August, and means sheep would have picked up immature fluke in June.
“But every year is different, which is why monitoring for fluke infection is so important.
“This year we had an exceptionally dry spring and early summer. As a result there should be a lower number of eggs and mud snails on pasture, despite the high rainfall later in the summer.”
Resistance to triclabendazole, the only active ingredient which can kill all the life stages of the parasite, is now moving up the agenda.
But determining whether this is the case on a particular farm needs a focused approach, as there are a number of other reasons why treatment may not be fully effective and appear to fail, explains Mr Walker.
He says: “10 individual animals should be sampled at the outset to establish if fluke infection is present.
“If positive, these same 10 animals should be treated with a triclabendazole product.
“Administering the correct dose is essential. Animals should be weighed and dosed for the heaviest in the group and samples from the same 10 animals then collected and tested two to three weeks later, dependent on test type.
“If resistance to triclabendazole is confirmed, then the fluke control plan needs to be altered in conjunction with the farm’s vet.
“This will allow us to maximise the efficacy of the alternative flukicide treatments and limit the impact of fluke infection.”
Faecal samples can also be used to monitor fluke status, collected from livestock and submitted to a vet practice to check for the presence of liver fluke eggs.
Mr Walker says: “It is important to remember that fluke eggs will only be found in the faeces when adult fluke are present in the liver, but at certain times of year, particularly September to November, large numbers of immature fluke can be present in the liver.
“Fluke egg counts will be negative but treatment may be urgently required and, therefore, blood tests or post-mortems will be needed to make a diagnosis.
“Abattoir reports and the copro ELISA can also be used to monitor for active fluke infection.”
A NUMBER of different products are available to treat fluke, but not all of them are suitable for use at all times of year or in all classes of stock.
Mr Walker says: “Product choice can be difficult in animals producing milk for human consumption and those close to the point of slaughter due to withdrawal times.
“Discuss with your own vet, who will have a good knowledge of the products available and the risks both on your farm and within the local area.”
Taking faeces samples for fluke egg counts
Source: Armour Vets