What's the issue?

Anthelmintic resistance is a serious and increasing threat to the health and welfare of livestock. If unchecked, it could lead to existing anthelmintics becoming ineffective, with a potentially catastrophic impact on animal welfare and production.

In the UK, resistance is reported mainly in gastrointestinal nematodes and, increasingly, in liver fluke. Currently resistance significantly impacts the efficacy of the 3 older classes of anthelmintics but is a threat against the efficacy of all anthelmintic groups.

What's our view?

Anthelmintics must be used judiciously as part of a farm-specific strategic anthelmintic plan, based on sound scientific principles.

Responsible use of anthelmintics

All prescribers of anthelmintics should be appropriately trained in parasitology, demonstrate commitment to continuous improvement through CPD and refresher training, and should:

• use diagnostic information for each parasite risk period to ensure treatment of only those animals that need it;
• target the drug used to the parasite to be treated;
• make sure that body weight is carefully calculated;
• understand the interplay of other host species and intermediate host species;
• advise that newly treated animals should not necessarily be moved immediately onto clean pasture;
• explain and emphasise the importance of quarantining incoming animals, assessing their parasite burden, faecal worm egg counts, and response to treatment;
• investigate suspected cases of resistance and advise on the selection of alternatives from other classes of anthelmintic drugs;
• report suspected cases of lack of efficacy to the Veterinary Medicines Directorate; and
• encourage holistic and integrated preventive strategies.

Suitably Qualified Persons (SQPs) should work with vets to follow the farm health plan.