Why is Resistance a problem?
If we continue to use worming products in a blanket manner i.e. just treating all horses regularly (whether they have high worm burdens or not) then eventually our worming treatments will become ineffective as the worms will be completely resistant to them. This could mean that there will be no effective treatment for horses suffering from the symptoms of high worm burdens, which will have a significant detrimental impact on equine welfare1.