Sheep dipping — immersion of sheep in a tank of organophosphate or synthetic pyrethroid insecticide solution — has been the traditional method of ectoparasite control in British sheep farming for over a century. While less commonly used than formerly, it remains relevant for controlling sheep scab (Psoroptes ovis) and other ectoparasites. Welfare and operator safety are key considerations.
Purpose and Targets
Dipping controls or prevents:
- Sheep scab — a notifiable disease caused by Psoroptes ovis mites; legal obligations exist around reporting and treatment
- Blowfly strike prevention (prophylactic dipping)
- Lice and tick control
Welfare Considerations During Dipping
The dipping process itself presents welfare risks requiring careful management:
- Correct swim-time is essential — sheep must be fully submerged for the required duration (typically 60 seconds) to ensure efficacy, but prolonged immersion risks drowning or aspiration
- Dip temperature management — cold dip solution causes hypothermia, particularly in recently shorn sheep; warming dip solution to 16–18°C reduces hypothermia risk
- Entry and exit ramp design — steep, slippery ramps cause falls and injury; adequate grip surfacing and gentle gradients are required
- Sheep held in dipper for correct time without distress — operators must count immersion time and assist sheep that are struggling
- Recovery areas must be dry and sheltered — sheep emerge wet and are vulnerable to chilling, especially in wind or cold conditions
Alternatives to Dipping
Injectable or pour-on treatments have largely replaced dipping for many producers:
- Injectable moxidectin — licensed for sheep scab treatment; single injection
- Flumethrin pour-on — effective for scab and lice; lower welfare risk during application than dipping
- Plunge dipping is still required where injectable resistance has been documented or where comprehensive louse control is needed
Operator Safety
Organophosphate dips (OPs) pose serious human health risks through skin absorption and inhalation. Health and Safety Executive (HSE) requirements mandate waterproof protective clothing, gloves, and respiratory protection. Many farms have moved away from OP dips entirely due to operator health concerns — synthetic pyrethroids are considered safer alternatives where effective.
Flock Health Planning
Ectoparasite control should be integrated into the flock health plan developed with the farm vet. This includes choosing appropriate products, monitoring resistance, and understanding when dipping provides genuine welfare advantages over alternative treatments. Sheep scab is a welfare emergency requiring immediate treatment — delays are never acceptable.