Recommendations for use of NEW orange group wormer for sheep (Lesley Stubbings)

October 2010

Recommendations for use of NEW orange group wormer for sheep

By Lesley Stubbings OBE, Sheep Specialist and Member of SCOPS (Sustainable Control of Parasites in Sheep) – the industry led initiative to slow the development of anthelmintic resistance

optiline-drenchingYou may have heard in the farming and smallholding press that a new broad-spectrum anthelmintic (wormer) group for sheep has been introduced – you’ll see it referred to variously as ‘monepantel’, which is the chemical compound name, ‘the orange group’ (which differentiates if from the existing white, yellow and clear groups of wormers), or ‘Zolvix’ which is the brand name marketed by Novartis Animal Health.

This is the first new type of wormer to reach the market for 25 years, and is a real breakthrough for sheep farmers, especially those farming in areas where there is parasite resistance to the existing 3 groups.  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, especially as the Group 3 – ML wormers are increasingly used against scab, as well as internal parasites.  In the UK we are in a better position than many other parts of the world, because it’s not too late – but we have to adopt sustainable worming practices now.

SCOPS has clear guidance for all sheep farmers, large and small, that will enable them to get the most benefit from the new orange wormer, while at the same time sustaining the effectiveness of the 3 other groups.  It starts from the moment you bring any sheep – whether new purchases, or your own returning from a show or outlying fields – onto your smallholding:

  1. YARD all sheep (ewes and rams) on arrival for 24-48 hours
  2. TREAT - drench with Group 4 – AD (orange ) monepantel, immediately followed by Group 3 – ML (clear) moxidectin (give each drench separately, DON’T mix them and give as one drench).  If you’re worried that sheep scab may be a risk, use 1% injectable moxidectin, or as directed by your vet
  3. QUARANTINE - following treatment, turn sheep out onto pasture that has carried sheep this season, and keep this group isolated from other sheep for at least 3 weeks

optiline-drenching2By following these 3 simple steps, you will ensure as far as possible that no drug-resistant worms are imported onto your smallholding.

Once the incoming sheep are integrated into your flock, SCOPS recommends that lambs are drenched with monepantel once a year, ideally during the mid-to-late season (August – September) when worm counts are high.  This is the best time to gain benefit in terms of reducing selection for resistance to the other 3 groups, and reducing the selection effect from the earlier part of the season.  An added advantage is that lamb performance can be improved as the lambs are cleared of any worms that may be developing resistance, and impairing lambs’ growth.

Speak to your own vet, who will also know of specific problems in your area, about incorporating these guidelines and practices into your own Flock Health Plan.





In Programme Two of the “Sheep on Your Smallholding” series – Managing Your Flock for Peak Health, Lesley Stubbings demonstrates correct drenching techniques with Adam Henson, and discusses the importance of giving the correct dose for the sheep’s weight, and ensuring that drenching equipment is properly calibrated.