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SCOPS Group welcomes new anthelmintic for sheep, but warns the sheep industry to use it carefully


The introduction of a new broad spectrum anthelmintic group (4-AD monepantel*) on to the UK market is an important addition in the fight to maintain good worm control in UK sheep flocks, says the SCOPS group. But, they warn, it does not take the pressure off the need to reduce our reliance on anthelmintics and it must be used carefully.

Resistance has become an ever increasing threat since the last new anthelmintic group was introduced to the UK market more than 25 years ago says Peter Baber, NSA and Chair of SCOPS. Monepantel offers farmers a valuable opportunity to maintain good worm control and prolong the effective life of the existing products. Following the SCOPS guidelines to carefully integrate monepantel into worm control strategies, before the other groups fail, will allow our sheep industry to reap the full benefits of this new novel group for longer he adds.

With respect to the application of monepantel, Lesley Stubbings, independent consultant says Controlling worms on farms with triple resistance is a clear application. However, by far the largest benefit will come from the integration of monepantel into the chemical control strategy on a farm at an early stage, before resistance levels are so high that other groups are no longer effective. Done carefully this allows us to reduce the selection pressure for resistance to the existing groups, keeping them effective for longer. In the UK we are in a better position than many other parts of the world, because its not too late for us to sustain the effectiveness of other groups says Ms Stubbings. But we must act now she stresses. With our [UK] ever increasing reliance on the macro-cyclic lactones (3-ML group) as endectocides for scab control, the pressure is really on if we are to maintain their effectiveness as a means of worm control she adds.

SCOPS believes that monepantel can have a major impact on worm control in the UK, but this depends heavily on Vets and advisers encouraging farmers to use it carefully, before double or triple resistance becomes more common, says Peter Baber. The industry has a major responsibility to exercise great care to protect the new group from over-use and mis-use to maintain its effectiveness. The application of SCOPS principles is more important than ever he adds.

* Zolvix Novartis Animal Health

How does SCOPS recommend monepantel is used on farms?

SCOPS has discussed at length how any new group should be used because the group believes it is vital that the industry is given guidance at the earliest opportunity. The guidance will be refined over time by monitoring the impact on farms, but initially two facets are clear.

  1. 1. Quarantine Treatment

Treatment of all in-coming sheep to prevent them importing resistant worms on to the farm has always been a cornerstone of SCOPS advice. The principle is that if sheep are treated with the two different groups with the least frequency of resistance in the worm population, the risk of any worms surviving is minimal. The advice now is that these two should be monepantel and moxidectin (the latter also covering for sheep scab if used in injectable form). The two to be given sequentially (see note below) , treated sheep held off pasture (yarded) for 24-48 hours and then turned out on to dirty (worm infested) pasture.

  1. 2. Integrated annually into the control programme

Evidence suggests that used once a year in lambs, in the mid/late season, when worm counts are high is the best time to gain benefit in terms of reducing selection for resistance to the other groups. This is because it [the new group] will kill worms resistant to the other groups, reducing the selection effect from the earlier part of the season. It may also help with lamb performance if this is being affected by the fact that less than 95% of worms are being killed where resistance is building, so performance is pegged back.

SCOPS encourages sheep farmers to talk to their Vet and/or adviser about how they might integrate monepantel into their worm control. The more information the Vet has about the farm, such as resistance status to other groups, the more effectively the product can be used said Neil Sargison, leading Sheep Vet and SCOPS group member. This is a great opportunity for Vets and farmers to work more closely and improve worm control while extending the useful life of the anthelmintics we have available he added.

Moving away from annual rotation of groups

SCOPS acknowledges that this advice means we are moving further and further away from the simple recommendation to change your wormer group annually says Lesley

Stubbings. What is important is that farmers know which group they are using and why. They must be prepared to use two or more groups in a season if it means they get the best worm control and performance, as well as the long term benefit of effective chemical control because they have minimised the risk that resistance will catch up with them. SCOPS will strive to give practical advice to sheep farmers to help then with their choices she said.

  • SCOPS is an industry led initiative to slow the development of anthelmintic resistance (AR). It is Chaired by NSA Chairman Peter Baber and has published a comprehensive Technical Manual (V 3 March 09).

  • Membership includes: NSA; AHDA; AMTRA; NOAH; VMD; NFU; SNFU; Welsh Assembly; SERAD; Defra; VLA; RUMA; SAC and independent advisers.

  • Sequential use of products means they are administered one after the other at the same handling. They should never be mixed prior to administration.

  • SCOPS is updating the leaflet it produces annually covering all sheep anthelmintic products available to include all changes and the new 4-AD group to which monepantel belongs. This is part of the SCOPS commitment to revision of clear information for farmers and advisers on the effective use of anthelmintics. A PDF copy will be available from 1st April 2010

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