Internal and external parasites are major causes of welfare harm in sheep, requiring integrated management approaches that reduce chemical dependence.
Sheep parasite welfare is a complex challenge at the intersection of individual animal health, flock management, and antimicrobial stewardship. Heavy worm burdens cause anemia, protein loss, weight loss, and in severe cases death — welfare harms that accumulate progressively without timely treatment. However, the widespread development of anthelmintic resistance threatens the long-term effectiveness of the chemical tools on which sheep farming currently depends. Integrated parasite management that combines targeted treatment based on clinical indicators, refugia-based resistance management, and pasture management strategies maintains both individual sheep welfare through effective treatment and the long-term effectiveness of available treatments.