B+LNZ Wormwise programme

Drenching

Many worms are developing the ability to tolerate the chemicals that once killed them – this is known as drench resistance. Find out about testing for resistance, and drench use strategies that slow down the development of resistance, including refugia and quarantine drenching.

For details on how to properly administer the various formulations of drench, please see the Drenchwise poster (PDF, 2MB).

For background on withholding periods for treated animals, please see the MPI Ground Rule ‘Withhold animals and products that may contain residues’. A list of all registered drench products in New Zealand, including their instruction labels and withholding times, is available on the ACVM Register. Select ‘Product Type’ and then ‘Endoparasiticide’.

images of drenches

Drench families

Here you’ll find details on the different anthelmintic classes available in New Zealand – what worms they target, how they act, and what we know about drench resistance for each class. 

image of drench diagram

Drench resistance – who cares?

Drench resistance is evolution in action (remember Darwin?). Here we examine the risk factors for developing drench resistance on your farm. We also show you what you can do to assess your own situation.

illustration showing refugia in sheep

Refugia

The term ‘Refugia’ can be really confusing! The outcome we want is to stop your farm from becoming dominated by drench-resistant worms. Using Refugia means leaving some worms free to breed without ‘screening’ by drench. There are various ways to achieve this. 

illustration of sheep and one odd one out

Quarantine drenching

Learn about when you should administer a quarantine drench, what to use, and importantly – what to do afterwards.

illustration of medicines

Alternative worm treatments

A range of different ‘natural’ products, herbs and minerals are sometimes advocated as treatments or preventives for worm infections in livestock. This page is by no means a complete list. But here we review some commonly mentioned ones, and available evidence for their efficacy.