Parasite Watch, Sheep farming

STARTECT: The Importance of Dual Active Wormers

Efficient sheep production relies on effective resistance management. Until this is part of a robust flock plan; money is being wasted all over the country. The reality is that most, if not all, UK sheep farms will already have some worms that carry resistance genes affecting production.

What are Dual Active wormers?

A Dual Active contains two anthelmintics from different classes, not to be confused with Combination Treatments which contain both a wormer and flukicide. A Dual Active specifically targets roundworms (for more information see SCOPS - know your anthelmintics).

How does a Dual Active Work?

The key to success is additive efficacy, as the wormers are from different groups, what survives one active will be killed by the other active, so in simple terms, you are doubling your chances of success:

However, the key to resistance management is the dilution of resistant worms by susceptible worms “in refugia” on your pasture, what is very important is not how many are killed by your wormer but how many resistant worms are left behind.

How will Dual Actives benefit me?

As Dual Actives are more effective than the individual components, the result is two-fold. Firstly an improvement in growth rate, worms which have survived treatment reduce growth rate and hence productivity, removing more of these resistant worms means improved growth rate in the treated lambs.
Secondly, as more resistant worms have been removed, the greater the dilution effect on pasture, meaning delayed resistance development1, meaning longer term drench performance on your farm.

When should I start to use a Dual Active?

Dual Actives should be used as part of your worming plan now, there is no point in leaving them on the shelf until it is too late, as the benefits will be greatly reduced. Early responsible use of Dual Actives will help to ensure that sheep roundworms are controlled sustainably now and far into the future.

What Dual Actives are available?

In the UK there is only one Dual Active available, containing the novel anthelmintic; derquantel and a group 3 wormer that has never been used before in the UK.  is the Dual Active wormer that should be part of your worm control plan.

When do I use STARTECT®?

STARTECT® should be utilised at quarantine time and as a late season Knockout Drench, A Knockout Drench is the substitution of one necessary lamb drench with a novel drench active. Resistant parasites which have accumulated and survived preceding drenches are then knocked out by STARTECT®; a Knockout Lamb Drench has been shown to delay the onset of resistance to the routine drenches².

The effect is time sensitive; the most useful time is later in the drenching programme but just prior to the time of most egg development or larval survival on pasture – i.e. late summer/early autumn. All sheep farmers should be adding a Knockout Drench into their preventative drenching programs.


Will STARTECT® work for me?

Zoetis are offering a Dual Action Guarantee with STARTECT®, that not only will it knockout resistant worms in the dosed lambs, but in comparison with your normal drench will improve growth rate. For further information click here.

How do I find out more?

Visit the website, to check out the facts and see videos from farmers and experts on the benefits for them and you or contact us via Twitter or Facebook.


1. Bartram et al, 2012, The role of combination anthelmintic formulations in the sustainable control of sheep nematodes
2. DM Leathwick & BC Hosking, 2009 Managing anthelmintic resistance: Modelling strategic use of a new anthelmintic class to slow the development of resistance to existing classes)

STARTECT® contains derquantel and abamectin, POM V. For further information please refer to the product SPC, or contact your veterinary surgeon or Zoetis UK Ltd, Walton Oaks, Dorking Road, Walton on the Hill, Tadworth, Surrey, KT20 7NS. Customer Support 0845 3008034. Always seek the advice of your medicines provider. Use medicines responsibly (