The SCOPS principles are designed to help slow the development on sheep farms. They are based on three main drivers for resistance:
- The frequency of anthelmintic use on a farm - every treatment selects for any resistant parasites present in the animal.
- The efficacy of each treatment – the accuracy of the dose and application, together with the level of resistance present to that product.
- The proportion of the total worm population in the animal at the time of treatment and how quickly any surviving parasites are diluted with unselected parasites in refugia of each treatment.