Fly strike — blowfly myiasis — is one of the most acutely painful welfare conditions affecting sheep. Prevention through targeted management is far more humane than allowing the condition to develop.
Fly strike causes extreme acute suffering. Blowfly larvae consume living tissue, creating progressively enlarging wounds that are deeply painful and can cause systemic illness and death within days. Affected sheep show agitation, biting at themselves, and eventually collapse as infection spreads. The welfare case for prevention is overwhelming: chemical prophylaxis and regular physical inspection are far preferable to treating established cases. Farmers managing fly strike need to balance the environmental impact of preventive chemicals — some have environmental persistence concerns — against the animal welfare imperative of prevention. Targeted treatments, applied to high-risk areas and during peak risk periods, minimise environmental impact while maintaining welfare protection. Prompt treatment when fly strike is discovered, including wound cleaning and antiparasitic application, is essential for minimising suffering duration.