Many sheep have died and more have been left emaciated following one of the worst epidemics of liver fluke seen by Alnorthumbria Veterinary Group. Veterinary Surgeon and Alnorthumbria Director John Macfarlane’s predictions that the parasite would take hold as a result of the long wet summer have been proved correct with acute and chronic cases arising county wide.
To discuss the damage fluke has caused over recent months, and to focus on preventative methods and treatments for the future, Alnorthumbria Veterinary Group are hosting a Fluke Meeting for both their Cattle and Sheep farmer clients. The meeting to be held on Monday 17th December will be held in two locations. The first meeting is at Newton-on-the-Moor at 12 noon at Cook and Barker where soup and sandwiches will be provided. The second meeting is being held at the Tankerville Arms, Wooler at 6.30pm with a hot meal provided. The meetings are sponsored by Elanco Health and to attend please contact your local branch.
Recently fellow Director Andrew Sawyer was called out to post-mortem seven ewes that had died very suddenly on a local farm. The post-mortem revealed classic signs of the disease and Andrew attributed liver fluke as the cause of all of the animal’s deaths. The infestation is now reaching critical levels and will be costly on the back of what has already been a very difficult season.
The post-mortem presentation of the disease includes blood in the abdomen, blood splashing throughout and a damaged liver with immature or adult fluke throughout. Predicting the illness from the outside of a live animal, however, can be more difficult but farmers can typically expect to see weight loss due to anaemia, loss of wool quality and occasionally bottle jaw where the sheep develops an accumulation of fluid under the jaw.
Farms with high stocking densities are particularly vulnerable, as are animals that are kept on land prone to flooding. The life cycle of the liver fluke begins when the worm’s eggs pass out of sheep or cattle via dung. They then hatch to form miracidia and then the parasite uses the mudsnail as an intermediate host. For each individual miracidium which enters the mudsnail, around 600 cercaria will emerge. These then migrate onto the grass and turn into metacercaria to be consumed by livestock. This life cycle thrives in wet and poor draining pastures, “a recipe for disaster” according to John, following on from the extremes of rainfall seen across the county over the course of the year.
As they enter the sheep’s body the larvae head straight for the liver. An adult worm is only approximately 2.5cm long; however one sheep can carry in excess of 30 fluke larvae with each consuming around 2ml of blood each day as well as producing eggs which starts the cycle all over again.
Diagnosis is made by your vet who will assess dung samples for fluke eggs, blood samples (which, if infested, will reveal raised liver enzymes) or by finding mature flukes demonstrated in the bile ducts and gall bladders at post-mortem.
John adds that, “Different fluke treatments have different applications so it is critical to speak to your vet about the right approach to diagnosis and treatment, especially in light of the very high level of challenge this year. Another problem that we are facing this year is assessing retreatment intervals. Normally treatment twice a year is adequate but around the UK we are hearing of situations where retreatment every five weeks is necessary. Retreatment intervals will depend on how bad pasture infestation levels are and grazing intensity. A new dung sample test will be available soon which should make retreatment timing more accurate”.
This summer’s wet spell does present an opportunity to establish your farm’s fluke status, if you haven’t already done so. It would also be prudent to check for triclabendazole resistance as three veterinary practices in Northumberland have now uncovered resistance on their farms.
For more information about Alnorthumbria Veterinary Group call 01665 510 999.
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