Best Practice Information Sheets (Westcountry Rivers Trust)

Pest management

Best Practice
Information Sheet

Sheep pest management

IS 2.6.3

Why change?

Good practice is essential for sheep pest management. All sheep pesticide products contain hazardous substances. If mishandled, they can make you ill, harm the sheep or pollute the environment. Review your sheep pest management and benefit from:

  • reduced risk of pollution
  • improved flock health
  • reduced risk of legal costs, fines and negative publicity
  • reduced risk of operator illness
  • decreased input costs.

Steps to success

  1. Review the current situation by examining sheep pest management on your farm. Consider your flock management, the nature of pest infestations, effectiveness of your pest management techniques and the risks of pesticide use to humans and the environment.
  2. Identify potential opportunities for improving your sheep pest management. If you can identify hazards to stock or human health or the environment, consider alternatives or improvements to your current practices.
  3. Calculate the cost-benefit of these opportunities by considering the cost of improved sheep pest management such as flock management changes, alternatives to plunge dipping and contractor costs, versus the potential savings of reduced risk of pollution and prosecution, improved flock and human health.
  4. Develop an action plan for improved sheep pest management on your farm:
    • be aware of the potential risks of using chemical controls. Organophosphates (OPs) may pose serious risks to human health whilst synthetic pyrethroids (SPs) are severely damaging to aquatic habitats. It is therefore essential to follow good practice guidelines and the manufacturer's instructions
    • restrict your use of chemical controls. Manage your flock to reduce the risk of infestation. Only use chemical treatments when they are strictly required for animal health reasons. Check your stock regularly to identify pest problems early. Target specific parasites with the most appropriate treatment to minimise costs and environmental damage, and to maximise efficiency
    • consider alternatives to plunge dips to minimise exposure and protect the environment. Authorised alternatives include pour-on products to control blowfly in scab free areas, injectables for scab control and pour-on products to control ticks
    • be careful when disposing of pesticides. Plan a safe disposal strategy pre-treatment. Disposal of sheep dip to land requires written authorisation from the EA. The recommended on-farm-spreading rate for spent dip is 5000l/ha (450 gallons/acre). Consider the use of detoxifying chemicals in spent dip to reduce pollution risks. Never empty dip wash into watercourses. Refer to Defra publication Groundwater Protection Code Use & Disposal of Sheep Dip PB5803.
    • prepare an emergency plan to minimise the potential impact on human health and the environment
    • consider hiring a contractor for sheep pest treatment and subsequent pesticide disposal.
  1. Check your flock regularly to manage pests early, to maximise economic returns and to minimise costs and environmental impact.
  2. Monitor the health of all staff exposed to pesticides and seek medical advice if any illness develops while dipping or soon afterwards. Medically confirmed cases of OP poisoning must be reported to HSE under the Reporting of Injuries, Diseases and Dangerous Occurrence Regulations, 1995.


Best Farming Practices: Profit from Change

Practical examples

Sheep are very susceptible to the sheep scab mite (Psooptes ovis) and infection can occur through brought in sheep, transport, common grazing, borrowed rams and markets. Prevention is always better than treatment for sheep scab, and knowing where any replacement or store sheep come from and segregation for a quarantine period is certainly cheaper than having to treat the infected flock. Decent fencing to prevent straying and mixing of sheep is most advantageous.

Moorland and common grazing are traditional hotspots of the mite, where dipping may be the only method of guaranteed cover. However injectibles are now claimed to have good cover against re-infection; up to 4 months in the case of Cydectin.

Treatment for Scab Cost/sheep (2006) Withdrawal period Worm control
Blowfly etc
Dip 30p 28 days no yes, 6 weeks
Ivermectin 60p 30 days yes no
Dectomax 75p 56 days yes no
Cydectin 89p 70 days yes no


Control of Blowfly and other Ectoparasites

A number of different controls are available for ecto-parasite control including dips, either as plunge dipping or by showering, using a machine or Knapsack sprayer. The volume of dip needing disposal is considerably smaller with a shower system and negligible using a Knapsack sprayer.

For the prevention of blowfly only, Vetrazin is the most effective, but does not treat animals with maggots already present. It is the only chemical allowed by the Organic bodies for the prevention of blowfly. For actual treatment of maggots the Organic bodies do allow “Spot on” at a dose of 5ml/ sheep costing 62p. Crovect is effective in both treatment and control of blowfly and ticks.

Cost/sheep (2006) Withdrawal
Dip 30p 28 days yes yes yes 6-8 weeks
Shower 15-25p 28 days yes yes yes 5-6 weeks
Vetrazin 40-60p   3 days yes no no 8-10 weeks
Crovect 50p   3 days yes yes yes 6-8 weeks




Disclaimer - Whilst the Westcountry Rivers Trust, its servants and agents (the "Trust") will use its reasonable endeavours to ensure the accuracy of its work, its advice involves matters relating to the natural environment or matters outside its reasonable control. Accordingly, other than personal injury or death arising from its negligence, the Trust will not be liable for any loss or damage howsoever arising directly or indirectly from any act, omission, neglect or default on its part. Funding for updating these information sheets was provided by the Water Quality Division of Defra as part of its England Catchment Sensitive Farming Delivery Initiative. These sheets provide practical information, guidance and recommendations for farmers based on Trust experience. © Westcountry rivers trust, 2007.

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