Animal Welfare and Antiparasitic Resistance

The growing resistance of parasites to antiparasitic drugs threatens both animal welfare and the effectiveness of welfare-critical treatments.

Key Facts

Benzimidazole resistance in sheep roundworms (Haemonchus) is now nearly universal in many flocks
Ivermectin resistance in equine small strongyles is increasingly documented
Overuse of antiparasitics in livestock and companion animals drives resistance development
Strategic selective treatment based on fecal egg counting reduces resistance without compromising welfare
The welfare implications of losing effective anthelmintics are severe for many species

Welfare Considerations

Antiparasitic resistance represents a slow-moving welfare crisis with potentially catastrophic consequences if effective drugs are lost. Parasite burdens in livestock and companion animals cause significant welfare harm - barber's pole worm (Haemonchus) in sheep causes anaemia, weakness, and death; strongyle burdens in horses cause colic and ill-thrift; flea and tick burdens in companion animals cause intense pruritus and transmit serious diseases. Strategic selective treatment programs that use drugs only when necessary, based on fecal egg count monitoring, reduce resistance development while maintaining effective control - a welfare-positive approach to antiparasitic stewardship.

What You Can Do

Work with your veterinarian on strategic selective treatment programs for livestock and horses
Monitor fecal egg counts rather than treating on schedule to reduce resistance pressure
Rotate between drug classes only when resistance testing justifies it
Support research into alternative parasite control methods including vaccines and genetics
Engage with veterinary professional bodies on antiparasitic stewardship guidelines