Sheep Fly Strike Prevention | Animal Welfare Hub

Blowfly strike is one of the most painful and distressing conditions affecting sheep. Prevention-first approaches using integrated management significantly reduce the welfare burden of this devastating condition.

Key Facts

Blowfly strike occurs when blowflies lay eggs on sheep, typically around soiled wool, wounds, or flystrike-damaged skin; hatching maggots cause severe tissue damage
An affected sheep can deteriorate from first strike to life-threatening condition within 48-72 hours; detection requires daily welfare checks during high-risk periods
UK sheep farmers lose approximately 3 million pounds annually to blowfly strike in treatment costs and mortality; the animal welfare cost is immense
Preventive organophosphate dips have environmental and toxicity concerns; newer preventive treatments including cyromazine and dicyclanil have better safety profiles
Selective breeding for reduced dag and breech wrinkle reduces susceptibility to flystrike and represents a long-term welfare improvement pathway

Welfare Considerations

Blowfly strike causes suffering that is both acute and entirely preventable. The welfare experience of a sheep with established strike — maggots consuming living tissue, pain, toxaemia, and progressive deterioration — is severe. Yet the condition is entirely preventable through a combination of preventive treatments, improved fleece management, selective breeding, and daily surveillance during the high-risk summer period. Farmers who experience high strike rates commonly have management gaps in one or more of these areas. The economic cost of strike, which is substantial, should motivate welfare-positive prevention, yet cultural normalisation of strike as an unavoidable risk of sheep farming has historically limited adoption of the best preventive practices. Welfare assurance schemes that monitor and benchmark strike rates between comparable farms expose this variation and create the accountability needed for improvement.

What You Can Do

Apply preventive blowfly treatments to all sheep before the start of the high-risk season in late spring
Conduct daily welfare checks for blowfly strike during summer months — early detection within 24 hours dramatically improves outcomes
Shear sheep before the high-risk period and manage breech wool to reduce the moist, soiled conditions that attract flies
Support selective breeding programmes for sheep with fewer dag-forming traits and less breech wrinkle susceptibility
Advocate for farm assurance schemes to collect and publish blowfly strike incidence data to benchmark farm performance