Internal parasites cause significant welfare harm in horses, but resistance to anthelmintics is a growing problem. Strategic treatment based on faecal egg counts protects both horse welfare and drug efficacy.
Equine parasite management sits at the intersection of individual horse welfare and the broader welfare concern of preserving effective treatments for future use. Routine suppressive treatment of all horses regardless of individual burden is no longer recommended because it drives resistance without improving welfare in low-shedding horses. Strategic targeted treatment guided by faecal egg counts protects high-burden individuals while reducing unnecessary treatment of horses who do not require it. Colic caused by mass emergence of encysted cyathostomins is a severe welfare emergency that can be partially prevented by appropriate autumn treatment with encysted-stage-effective products. Pasture management that reduces reinfection pressure complements targeted treatment to achieve good parasite control with minimal drug use.