Keep your horse healthy while helping to protect the wormers we rely on with a targeted, test-led approach to parasite control.
Worm control has changed. Regularly worming every horse at fixed points throughout the year is no longer considered best practice for mature horses – and may ultimately put them at higher risk of disease. Instead, current advice is to assess each horse's risk, use appropriate diagnostic tests and only treat when there is a good reason to do so. And to focus hard on reducing grazing horses’ risk of acquiring worms in the first place, for example: if people practice good pasture management (especially regular poo picking) then they will be going a long way to winning the battle of worm transmission, It’s also worth being mindful of where your horse grazes away from home, such as at events, as unfamiliar pasture may expose them to parasites, including potentially resistant parasites.
This matters not only for your horse's health, but for the future of parasite control. Resistance has now been reported to all classes of wormer currently available in the UK, and there are no new classes waiting in the wings. Using wormers only when they are genuinely needed helps preserve their effectiveness.
Faecal worm egg counts (FECs) are an important part of a modern parasite-control programme. A small sample of fresh droppings is sent to a laboratory, which measures the number of parasite eggs being shed and reports the result as eggs per gram (epg). However, please be aware that FECs don’t reliably detect tapeworms.
Regular FECs should be carried out while horses are grazing, with the frequency determined by the horse's individual risk, previous results and management. However, as every yard’s situation is different, it’s important to work with your vet to develop an appropriate parasite management and testing strategy, including how frequently testing should be carried out.
However, a low worm egg count doesn't mean your horse is completely worm-free. FECs measure egg shedding rather than the horse's total worm burden, and they cannot reliably detect every parasite or life stage. In particular, they cannot tell you whether a horse has a significant burden of encysted small redworm larvae.
For mature horses without signs of disease, a treatment threshold of more than 200–500 epg is commonly used. In low- to medium-risk adult populations, the higher threshold of more than 500 epg may be appropriate. Results should always be interpreted alongside the individual horse's age, health, history and management. Again please consider discussing with your vet the results.
Rather than automatically treating for tapeworm once or twice a year, current advice for mature horses is to test first and treat where results indicate significant exposure.
Saliva and blood tests can measure antibodies against tapeworm. These indicate exposure rather than directly detecting living worms, so results need to be interpreted appropriately. Check the package insert for the test’s specific guidance, as testing too soon after treatment for tapeworm may result in uninterpretable results.
For many well-managed adult horses, testing once a year is a reasonable starting point, although horses at greater risk may benefit from more regular testing.
Not necessarily.
Historically, owners were commonly advised to give every horse a larvicidal treatment during autumn or winter to target encysted small redworm. Current guidance for mature horses is more targeted. And remember, FECs won't tell you re encysted cyathostomin levels.
The risk of disease caused by encysted small redworm should be considered alongside the horse's age, management, previous worm egg counts and treatment history. Routine larvicidal treatment is now discouraged in mature horses that repeatedly have low FEC results and are managed in a way that puts them at low risk.
A blood test for small redworm exposure is also available, but current guidance is that it should not routinely be used on its own to decide whether to treat. Speak to your vet about the most appropriate approach for your horse.
Resistance means we can no longer assume that giving a wormer has successfully treated the parasites present.
Where treatment has been necessary, a faecal egg count reduction test (FECRT) can help assess whether the wormer has worked effectively. This involves carrying out another FEC approximately 10–14 days after treatment.
Where horses on a premises require worming, checking treatment efficacy annually can help identify emerging resistance and guide future parasite-control decisions.
