Sheep farming

Be prepared to give mid-summer fluke treatment to sheep

Acute fluke in sheep is expected to be a risk earlier this summer following the wet winter. This makes a mid-summer treatment vital to prevent significant losses.

Despite the brief cold snap seen at the start of the year, it is expected the mud snail, which is the fluke’s intermediate host, will have thrived in the damp and wet conditions. This means there will be a build-up of infective metacercariae on many pastures, which develop into immature fluke when ingested.

As a result, it is expected that there will be an earlier risk of immature fluke in grazing sheep this year, which can lead to death when not treated.

Farms involved in the Zoetis Parasite Watch Scheme, are already picking up cases of fluke. All farms that contain wet areas could be at risk of fluke, anywhere that is wet, such as around gateways and water troughs, can provide the ideal location for the mud snail.

Management and testing

For sheep, constant management of fluke is necessary because there is often no break in the grazing cycle. So, with no product persistent against fluke, a sheep treated one day can pick up infection the next if they are grazing infected pasture.

It is important to be aware of what is happening on the farm, although faecal egg tests will pick up fluke that are 12 weeks old, it won’t pick up immature fluke, which can cause acute disease and sudden death. Copro-antigen testing will pick up fluke from about six weeks old meaning that a negative test doesn’t discount the presence of fluke under six weeks of age.

It is always a good idea to use testing along with other resources, such as abattoir feedback, and general stock health to make a decision on treatment
Farmers can monitor fluke and worm levels in their area by clicking on an interactive map found at

Parasite data from farms involved in the Zoetis Parasite Watch scheme will be updated regularly, which will allow farmers to see if there are spikes in certain parasites throughout the year in their area and enable them to take appropriate action. To use the map, click on a farm in your area and details of any parasites that have been found as well as when they were detected will be displayed.

Fluke treatment in sheep

For sheep, it is the immature fluke that can cause the most damage as they migrate through the liver. A heavy burden can lead to sudden death, due to damage or by predisposing to clostridial disease. When selecting treatment options mid-season, it is vital to consider the age of the fluke being treating for.

Many fluke treatments focus on killing egg-laying adults, meaning most immature fluke will still be present; these will continue to cause damage as they migrate through the liver. These will go on to develop into adult fluke.

Triclabendazole is the only ingredient that is effective against fluke from two days old with other products, such as closantel and nitrozynil, effective on fluke over six weeks old. However, their efficacy at this stage in sheep is only 50-90% effective compared to the 99-100% effectiveness of triclabendazole1.

If there is a mixed worm burden, using a broad-spectrum combination product, such as CYDECTIN® TriclaMox®, which contains moxidectin and triclabendazole will be effective against worms for up to eight weeks and is also effective against immature fluke. Then other flukicides should then be used in rotation to target the stage of fluke causing the problem. It’s very important to have a plan in place and make sure treatment is for the risk at that time.


  • Potent Combination
    • Contains moxidectin providing persistent
      worm control
    • Contains triclabendazole effective against all stages of fluke
  • 35 Days Worm Persistency
  • Treats All Stages of Fluke
  • First Choice ML to Delay Resistance

1. Fairweather, I and Boray, JC (1999) Mechanisms of fasciolicide action and drug resistance in Fasciola hepatica. Chapter 7 In Fasciolosis, Ed JP Dalton. CAB International. pp 225-276
CYDECTIN TRICLAMOX 1 MG/ML + 50 MG/ML ORAL SOLUTION FOR SHEEP contains moxidectin and triclabendazole. POM-VPS For further information please see the product’s SPC or contact Zoetis UK Limited, Walton Oaks, Dorking Road, Tadworth, Surrey KT20 7NS. Customer Support: 0845 300 8034. Use medicines responsibly ( Date of preparation: May 2018 AH328/18