How to best check your sheep flock for fluke

Acute fluke is already being detected in condemned livers at abattoirs this autumn, with experts predicting the challenge in some areas to be significant.

Sheep vet Matt Colston from Elanco Animal Health, says last week he saw condemned livers with 3-5mm long fluke, despite lambs being fit enough to get to the slaughterhouse.

“This shows there is a real liver fluke challenge at the moment, but not every farm or field will have a challenge,” says Mr Colston.

See also: Fluke survey reveals only 8% of farmers are treating correctly

He says the liver fluke cycle is largely dependent on weather, with the level of challenge to grazers in the autumn being related to rainfall in late spring and late summer.

“This varies from farm to farm, and also depends on there being suitable habitats for the mud snail [Galba truncatula], which is the intermediate host for the liver fluke.

“Understanding this link between weather and the fluke challenge – and the need to act accordingly – is vital,” he adds.

Surveillance farms 

Elanco Animal Health has set up five surveillance farms to monitor fluke risk.

The farms will be working with industry experts and their vet to test, monitor and help manage a sustainable approach to liver fluke control on their farm, with results reported in Farmers Weekly every month until April 2016.

Farm profiles

• Farm one George Milne, Kinaldy Farm, Fife: 120 pedigree ewes and lambs, 500 gimmers and 250 fattening hogs. Experienced large losses to fluke in the winter of 2012-13.
• Farm two John Harrison, Croftheads, Dumfries and Galloway: 200 Lleyns and Hampshires ewes.
• Farm three Paul Capstick, Parkhouse Farm, Heversham, Cumbria: 1,000 mule ewes.
• Farm four Carwyn Roberts, Garn Fach, Llanelli: 270 ewes.
• Farm five Mr Peter Derryman, Peterhayes Farm, Honiton, Devon: 100 pedigree Hampshire Downs, 120 pedigree Suffolks and a commercial flock of 250 Romneys.

Results

Results from September already show some farms have a fluke challenge and active infection.

See also: How to treat and manage liver fluke

Commenting on the results (see table 1), Mr Colston adds: “Although it would appear farms one and five have lower levels of fluke challenge than the others, that does not mean there is no fluke activity on those farms, it just means those particular lambs have not met any liver fluke yet.

“In fact, farmers should expect a fluke challenge to be happening now in grazing areas where there are snail habitats,” he says.

Which test to use

Mr Colston encourages farmers to find out whether their stock has been exposed to fluke by blood testing this year’s lambs for antibodies.

If blood results come back positive for exposure, then he recommends a follow-up test using a copro-antigen and/or a faecal egg count test, which should be done in consultation with a vet. Both tests are valid, but measure different things.

• A copro-antigen test on a dung sample, detects active fluke in the liver, but only when there’s enough of a challenge. The copro test will give a positive result earlier than a faecal egg count, when there is a enough of a challenge, and will go positive about six to eight weeks after infection.
• Alternatively a faecal egg count will not provide egg counts until 10-12 weeks after infection and they don’t give you an idea about how much fluke there is.

“Mr Colston says in situations where both a blood test and copro-antigen test are positive then stock should be treated with a flukicide.