Reducing Resistance to Wormers
Resistance occurs when a selected wormer no longer effectively controls the worm population and it is an increasingly common problem to all wormers. Once resistance has been established in a worm population, the health, welfare and performance of worm infested horses will be compromised.
Resistance may be increased when too low a dosage of a wormer is used for the weight of the horse, or if the wormer is used too frequently.
To help reduce the incidence of resistance we should:
- Use faecal worm egg counts to determine whether a wormer is needed. Four faecal worm egg counts are included when you join the Horse Health Programme.
- Avoid using one particular active ingredient of wormer all the time.
- Weigh (or weigh tape) our horse/s before dosing and avoid under dosing.
- Rotate the active ingredient/class of wormer used for each grazing season.
- Target specific worms with an effective product at the correct time of year.