Sheep Flystrike Prevention: Welfare and Management Strategies

Flystrike is one of the most painful and welfare-significant conditions affecting sheep, requiring active prevention and rapid treatment.

Key Facts

Flystrike (myiasis) occurs when blowflies lay eggs in damp, soiled wool, and hatching larvae eat living tissue
Untreated flystrike causes severe pain, tissue destruction, toxaemia, and death within days
Merino sheep are particularly susceptible due to their wrinkled skin and dense fleece around the breech
Mulesing — removing breech skin folds — reduces flystrike risk but is itself a painful procedure
Chemical prevention, selective breeding for plain-bodied sheep, and regular monitoring are alternatives
Warm, humid weather and diarrhoea (dag) significantly increase flystrike risk

Welfare Considerations

Flystrike causes extreme suffering — affected sheep are often found with large areas of tissue destruction, in obvious distress and toxaemic collapse. Prevention is far more welfare-positive than treatment. Chemical preventatives applied at the appropriate seasonal timing, combined with regular inspection during high-risk periods, prevent the majority of cases. The mulesing debate illustrates the welfare trade-off complexity: the procedure causes acute pain but reduces chronic flystrike risk in vulnerable animals. Welfare-centred approaches increasingly prioritise selective breeding for breech conformation that reduces mulesing necessity, combined with management strategies that lower flystrike risk.

What You Can Do

Apply chemical fly prevention at appropriate seasonal timing in at-risk flocks
Inspect sheep at least twice weekly during warm weather and after periods of diarrhoea
Support selective breeding programmes for plain-bodied sheep that reduce mulesing necessity
Treat any case of flystrike immediately — it is a veterinary emergency
Look for wool products sourced from farms using mulesing-free production systems