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Use of combination drenches for worm control has been demonstrated to be superior to the practice of using single active drenches in rotation for delaying the development of worm resistance.

Results from an Australian study support the use of triple-combination drenches as an important pillar in controlling worms in sheep. A resistance model developed for sheep worms under Australian conditions showed that triple combination drenches slowed the development of resistance and extended the life of the drench.1 A single active drench program utilising one drench repeatedly was compared to both 2-way and 3-way drench combinations used at the same frequency (Figure 1). The actives within the combination drenches represented unique drench classes with differing modes of killing worms (eg. white/clear/ML).

Using a drench until it would no longer prevent major production loss associated with worm infestations, the model predicted that following the repeated use of a drench, the drench life would be:

  • 4 years for a single active drench
  • 12 years for a 2-way combination drench
  • ≥30 years for a 3-way combination drench

Additionally, the researchers showed that there was no advantage in utilising various rotation strategies between different drench actives, and that the multi-active combinations out-performed 2 actives used within a rotational program. This provides strong supportive evidence for the use of triple-combination drenches like TRIGUARD.®


Figure 1: Development of drench resistance when one, two and three-active drenches are used1.

The greatest benefit for extending the life of the drench comes when combination drenches are adopted prior to the onset of worm resistance to any one of the active drench classes. Therefore, it is important that farmers do not wait for resistance to appear before making the switch to a combination product like TRIGUARD. Early adoption means greater exposure of susceptible worms to the 3 different actives, so the product is likely to be more effective for a longer period of time.

This work correlates with previous work2 and provides yet more compelling evidence for farmers to be using multi-active combination drenches.

Choose TRIGUARD for a highly effective, broad-spectrum, triple-combination drench to control worms and help manage resistance now and into the future.