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Worm control

Effective worm control relies on the correct and responsible use of wormers combined with good pasture management.

  • Use faecal worm egg counts (FWEC) during the grazing season (approximately every 12 weeks) to assess whether your horse needs worming.
  • Target the following worms at the correct time of year with an appropriate wormer:
  • Tapeworm and encysted small redworm larvae – late autumn/winter
  • Your vet will advise on an appropriate wormer. There is a wormer available which includes both praziqantel (which treats tapeworm) and moxidectin (which treats encysted redworm larvae & bots as well as large and small redworms, roundworms & pinworms) so it is possible for tapeworm to be treated at the same time as encysted redworm and bots.
  • All horses and ponies on the yard which need to be wormed should be all wormed at the same time.
  • Use the correct dose. The recommended dosage will vary according to the horse’s weight. Estimate weight as accurately as possible using a weigh bridge or a weigh tape.
  • Don’t rely on the blanket use of the same wormer; This may encourage the development of drug resistance in the worm population.

There are four main classes of anthelmintics (wormers). These are:

  • Benzimidazoles:  fen/me- bendazole.
  • Tetrahydropyrimidines: pyrantel embonate.
  • Macrocyclic lactones: Iver/aver -mectins.
  • Praziquantel based wormers (tapeworm treatment ONLY).

A well-managed pasture will help to reduce the worm burden. The following points should be followed where possible:

  • Remove droppings on a regular basis (preferably daily, but at least twice a week) and don’t use horse manure as fertiliser.
  • Don’t overstock pastures: a maximum of two horses per hectare or 1-1.5 acres per horse is recommended.
  • Graze horses of a similar age together – young horses are more susceptible to a higher worm burden.
  • Sub-divide grazing areas into smaller paddocks and graze on a rotational basis.

Graze paddocks with other livestock too. This will dilute the horse worm burden on your pasture.


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