WormBoss Drench Decision Guide

Worm infection costs the Australian sheep industry an estimated $436 million per year, most of which comes from lost production.

WormBoss is a website that deals with all facets of worm control in sheep and goats in Australia. It was initially developed in 2005 and has undergone several upgrades since then. Similar resources on dealing with flystrike control (FlyBoss) and lice control (LiceBoss) are available on the ParaBoss site.

WormBoss provides a variety of generic background information on worms, worm testing, drenches and service providers. It also provides regionally specific generic worm control programs; the Victorian Winter Rainfall program and the Pastoral Zone program for the Mallee and northern Wimmera, are applicable to Victorian sheep producers. You can also subscribe to monthly state outlooks which provide advice related to seasonal conditions.

WormBoss also provides several tools to assist with decision making, including regional Drench Decision Guides. This guide is available both as a step-by-step online tool and as a decision tree, which can be printed. The answers you provide in the online tool will result in the generation of  an advisory report relating to your particular scenario.

The first question relates to whether your sheep are showing clinical signs of worm infestation. Scouring and/or weight loss suggest scour worms, and anaemia and lethargy may indicate barber’s pole worm. The second question relates to whether the sheep are lambs or weaners. Weaners are among the most susceptible to the effects of worms because of their low immunity and their worm control needs to be managed strategically. The third question relates to whether the sheep are rams at the point of joining. The stress of joining lowers immunity and increases the potential for build-up in worm numbers.

The final question covers all other scenarios. It includes ewes at the point of lambing, as a pregnant ewes’ immunity to worms is often reduced around the time of lambing for up to two months. It also includes November and December, January and February, which are typically the times of the first and second summer drenches, respectively. These drenches are important in reducing worm numbers the following winter but also potentially increase the risk of drench resistance.

In each scenario, the regional Drench Decision Guide gives management advice relating to that scenario and drench advice based on the results of worm testing.

Effective worm control can be a complex subject so, in addition to the guides and tools that WormBoss provides, it is recommended that you seek advice from your veterinary adviser.

Page last updated: 12 Jan 2023