Treatment at this time of year should target adult flukes, say SRUC vets.

Despite a lack of recent epidemics, SRUC vets urge farmers not to forget the parasite

Vets from Scotland's Rural College (SRUC) have warned sheep farmers not to let down their guard against liver fluke disease, as despite this year's lack of epidemics, the parasite has not disappeared.

Liver fluke primarily infects sheep and cattle. Its life cycle includes a stage of parasitising a mud snail, after which it forms the infectious cysts that stick to vegetation, mainly during the autumn months. This vegetation is then grazed by sheep and cattle, allowing the cycle to continue.

Liver flukes are named after their tendency to migrate through the liver of their host organism, and develop in the bile duct. Infection leads to poor health, or even death as a result of liver haemorrhage and destruction.

As the mud snail host thrives in wet summers, the summer and winter of 2012 to 2013 had devastating consequences in terms of the effect on sheep health. These conditions have not been repeated this year but this is no reason for sheep farmers to stop taking precautions, SRUC says.

Heather Stephenson is a Dumfries-based vet from the SAC Consulting arm of SRUC. She says that there are two reasons why liver fluke has been less reported.

“The very welcome drier summer of 2013 put the brakes on fluke development," she says. "There were fewer wet areas for the mud snail that hosts the fluke during part of its life cycle, and this in turn meant there were fewer numbers of infectious cysts on the autumn grass for sheep to ingest.

"In addition, the increased awareness of fluke encouraged farmers to treat their stock for fluke which reduced losses”.

Farmers are advised to check dung samples for liver flukes to find out whether treatment is required. Treatment at this time of year should target adult flukes, so products which contain triclabendazole are not recommended, unless testing whether it works on your farm, as this is aimed at juvenile flukes.