Resistance by sheep worms to drenches in Australia continues to increase. To prevent the introduction of new strains of resistant worms onto a farm, purchased sheep or those returning from agistment should be given a quarantine treatment before loading or on arrival. The current minimum recommendation is to treat with three or four different drench types, including monepantel (Zolvix). The sheep should then be released into a wormy paddock to dilute any remaining 'super-resistant' worms.