Autumn Advice From Our Veterinary Parasitologist Expert
Professor Jacqui Matthews, RCVS Recognised Specialist
Equine Worm Control – Why Autumn is the Time to Act
We’ve had a few questions recently about “winter” worm treatments and testing. However, it’s important to start planning worm control in autumn rather than waiting until later in the season. Unless horses were treated recently, worm burdens are likely to be highest at the end of the summer grazing period because:
1. During summer, horses spend more time grazing, which increases their chances of picking up worms from paddocks.
2. UK summer weather conditions create the perfect environment for redworm and tapeworm infective stages to develop on pastures.
Autumn Worm Control: A Step-by-Step Guide
​
1. Start with a Risk Assessment
Evaluate each horse based on management, age, treatment history, recent test results and clinical background to categorise them as low, moderate or high risk for infection. Use the free online tool whatsyourwormrisk.com to assess individual risk.
2. Test for Tapeworm
Carry out a blood or saliva tapeworm test to identify horses that may be carrying tapeworm burdens that put them at risk of colic.
3. Treat High-Risk Horses for Encysted Small Redworm
For horses identified as high risk, consider a treatment for encysted small redworm.
4. Tailor your Approach for Low-Risk Horses
For low-risk horses, avoid unnecessary treatments to reduce wormer resistance selection pressure. The small redworm blood test can be used to confirm whether a horse has a negligible or low burden that does not require treatment at this time of year.
5. Make a Plan for Outwintering Horses
For horses that will spend some or all of their time at grass over winter, schedule the next faecal egg count around 10–12 weeks after the last test or treatment to monitor ongoing infection risk.
6. Plan Pasture Management for the Year Ahead
Remove dung from paddocks where horses are grazing at least once a week, year-round. Map out a 12-month plan - identify paddocks that can be rested (and for how long), and consider mixed grazing with ruminants — remember to risk assess for liver fluke and apply diagnostic testing where appropriate. Good pasture management is the most powerful tool for breaking the worm transmission cycle and protecting wormer effectiveness for the future.