Worming your Horse

Guidance on the best ways to control worms in horses

What do you know about worm control? Guidance on the best ways to control worms in horses has changed in recent years and it’s important to move with the times to help keep our horses healthy. The best way to do this is to talk to your vet.

So what’s changed about worm control?

Blanket worming every horse on the yard every few months is now regarded as very old fashioned and not very effective. In fact it can be counter-productive. The modern way is to tailor a specific plan for each horse; conduct regular faecal worm egg counts (FWECs) to guide targeted dosing in the summer and dose strategically for specific worms that don’t show in egg counts. There are important scientific reasons for the changes.

What’s wrong with the old worm control method?

In the same way that antibiotics are becoming less effective in humans and in animals, scientists have discovered that worms are becoming resistant to the drugs in some wormers and can survive, despite the horse being wormed. The development of these resistant worms increases if wormers are used indiscriminately. Currently, there are only four different drugs used in equine wormers so it is vitally important for us to preserve their effectiveness by using them in a responsible, targeted way.

The role of vets

Vets have the knowledge to guide you on the most up-to-date methods of worm control and it’s important to ask their advice before making any decisions about worming your horse.

So what is 21st Century worm control?

  • Faecal worm egg counts should be used every 8-12 weeks during the grazing season from around March to October and horses treated according to the results.
  • Tapeworm (don’t show up in FWECs) should be targeted once a year, usually in the autumn or winter using a single dose of praziquantel or a double dose of pyrantel or a specific tapeworm test conducted.
  • Bots (don’t show up in FWECs) should be treated annually after the ‘first frost’.
  • Weigh before worming to ensure you buy and give the right amount of wormer. Under-dosing can encourage worms to become resistant to the wormer you use and not be killed by it, creating a strain of resistant worms on your yard.
  • Use faecal egg count reduction tests during the grazing season: following a positive FWEC a second FWEC is recommended 2 weeks later to ensure your wormer has worked and reduced the number of worm eggs.
  • Encysted small redworm (don’t show up in FWECs) should be targeted in adult horses once a year in the late autumn or early winter using a single dose of moxidectin or a five-day course of fenbendazole. There is widespread evidence of resistance in small redworm to fenbendazole, including the five-day dose so a resistance test is recommended before using it.
  • Keep pasture clean: Daily poo-picking, regular rotation and resting of fields and cross grazing with sheep or cattle will help keep pasture worm burdens under control.
  • Keep a record: so that you have a history of the wormers used and the results of tests. Share this information with your vet or SQP to avoid overuse of the same types of wormer.
  • Seek advice: Never be afraid to ask for help. Always speak to your vet to discuss the best worm control programme for your horse and his environment.

Why can’t you tell me which brand of wormer I need to use?

In the same way as for antibiotics, it is illegal to advertise wormers to horse owners. Only the medicines prescriber, namely your vet or SQP, can advise you on which brand of wormer your horse requires. They have to ask certain questions to make sure that the correct wormer is prescribed at the right time of year and that it is the most suitable one for your horse’s individual needs.

View our worming care package