Article Text

Farm Animal Practice
Strategies to minimise anthelmintic resistance in large animal practice
  1. Gerald Coles

    Gerald Coles graduated from Cambridge with an MA in biochemistry and PhD in insect biochemistry. He worked in East Africa, the UK pharmaceutical industry and the USA before becoming head of the department of parasitology at the Central Veterinary Laboratory (CVL). He moved to Bristol veterinary school as senior research fellow after the closure of the department. His research interest is the control of parasitic infections with special reference to anthelmintic resistance.


AS veterinary surgeons are all too aware, infection with nematodes can cause serious welfare problems in both sheep and cattle, as well as costly production losses. Farmers have become accustomed to being able to control worms with anthelmintics, so the true significance of these parasites may have been largely forgotten. With increased stocking densities and intensive grassland management, nematodes potentially represent a more serious threat than they did before the introduction of broad-spectrum anthelmintics. It is unlikely that any new anthelmintics will be introduced onto the market in the near future, so loss of efficacy of existing products could pose severe problems for large animal practitioners and their clients. Anthelmintic resistance is already a serious problem in some parts of the world, not just in sheep and goats but also in cattle. A similar situation will develop in the UK unless steps are taken to prevent it. For sheep farmers, it will be, at best, like 'the good old days' when it was unusual to have lowland lambs ready for market before October; at worst, sheep stocking densities will have to be substantially lowered to reduce the risk of animal deaths. This article examines the current extent of the problem of anthelmintic resistance and discusses how it might be avoided.

Statistics from

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.