Worms - The Accidental Smallholder

The most common internal parasites of sheep are worms. There are three groups – roundworms, tapeworm and Nematodirus. There is a range of chemicals available to kill worms – but not all worms are equally susceptible to each type of chemical and some worms have become resistant to some or all the common wormers.

Fortunately, the chemical companies are hard at work to find new solutions. Wormers are available as oral drenches, injections and pour-ons, often in combination with other treatments.

If you want to eliminate the use of chemical wormers, because of their adverse impact on the environment, herbal wormers are available.

Grazing management

Grazing management can also help to control internal parasites; most worms have a limited ability to survive outside the gut so rotational grazing, low stocking rates and resting pasture can help to reduce worm infestation.

Multi-species grazing can also help because worms are species specific – so sheep can ingest (and destroy in the digestive process) cattle worms without ill-effect, and vice versa. Liver fluke, however, is not host-specific.

Whatever method or methods of worm control you are using, you should seriously consider using faecal worm egg counts. This involves collecting a faeces sample and sending it to a laboratory, where the sample will be examined for the presence of worm eggs. Kits are available or your vet will be able to help.

The presence or absence of worm eggs will give a good indication of whether or not your worm control strategy is effective.

We routinely worm all our sheep at lambing time; the ewes are dosed when they are turned out of the lambing shed with their new lambs and we do the tups and the previous year’s ewe lambs at the same time. We take faecal samples from the lambs over the summer – at shearing, when we dose with Heptavac and so on – and treat if required.

We test the ewes and tups before tupping and if any particular animal has diarrhoea or looks thin, we’d do an individual test. Tests only take 24 hours to come back from the lab.