George's Liver Fluke Journal: Entry 4

29th April 2014

George Milne, NSA Scotland Regional Development Officer, farms near St. Andrews on the east coast of Scotland. This is not a part of the world where fluke would be expected to cause major losses, but in the winter of 2012/13 that is exactly what happened. George has kindly let his farm be used as a fluke surveillance farm in a project funded by the Scottish Government and Novartis Animal Health, and supported by Moredun Research Institute, Scottish Rural College, University of Edinburgh , Parkside Vets and the National Sheep Association. The surveillance farm is part of the Scottish Fluke Action Group, a group representing many aspects of the Scottish sheep industry that aims to give real-time information to vets and farmers on managing fluke. George will be adding to his journal on a regular basis; you can read the first instalment of this story   here the second journal entry here and the third instalment here.

George’s Journal

The winter has gone very quickly and been mild but very wet here in Fife. The sheep, compared to last year, have been in great condition and with the farm restocked this spring looks very different to the one 12 months ago.

The last time I wrote, at the back end of last year, the fluke challenge had been much less than at the end of 2013 and, when we tested our groups in November, the animals had become infected with fluke but the coproantigen test, that measures a fluke secretion in the dung, and the fluke egg counts were both low.

As the animals were in lamb and to avoid any fluke-related stress to the ewes, sheep with closantel in January. This was the active chosen because the winter had been so mild there was still a chance that immature fluke might be present. It was decided, in discussion with my vet and the Fluke Action Group, that as the sheep were in very good condition we would leave 10 animals untreated as ‘sentinels’ to continue to monitor the fluke infection going into the spring.

Grazing

Last year there were definitely fields the sheep got worse infections in and I made a big effort in the summer to improve the pastures. The fluke needs a mud snail to complete its life-cycle so draining marshy areas, spraying the rushes and improving the areas around the gates has, I hope, also helped reduce the level of fluke the sheep faced this winter.

The question I always have with fluke is when do I need to treat them again, as it seems to change every year. There’s no straightforward answer but discussing with your vet or prescriber what other farmers are seeing plus using websites like www.nadis.org.uk will give some idea of the fluke challenge right now. We are also using testing to help with the decision and the vets came out at the end of March to take dung samples from the 10 individual sentinel animals plus some from the animals we treated in January.

The animals we didn’t treat in January now have high fluke egg counts and coproantigen so we now need to treat these animals. The animals that were treated have no fluke egg counts so they will not be treated yet. Due to the mild winter it is hard to know if they have picked up any new infection, but we will be retesting them in a few weeks.

The ewes are now lambing and we will be worming the ewes to stop them putting worm eggs onto the pasture to infect the lambs. After discussing with my vets, I will be leaving the ones carrying singles or ones that are in good condition to try and slow down the development of resistance to wormers on my farm. I learned the hard way that having resistance can have huge effects on the flock. The vets and I have discussed that resistance can develop to all wormers so it is essential to know what works but we will do this in the lambs in the summer.

My situation

The fluke situation on my farm and the way I am controlling it is specific for my farm and I know it will not be the same every year or on every farm. One thing I will be doing is taking a sample for fluke eggs in May, as if there are any eggs present I want to try and stop the snails getting infected this summer as that starts the problem for the autumn. The lab says it only needs to be a mob sample so I will only need to collect 10 fresh bits of dung from the field.

Next time we will see how the sheep that were treated in January are doing and see if they have any infection that needs to be treated to protect my pasture this summer.

George has been improving areas such as this to reduce snail habitats.
George (pictured left) left some of his ewes untreated in January, as 'sentinels' for fluke infection.