The New Approach to Horse WormingUpdated 4 hours ago
For many years, horse owners were advised to worm their horses at fixed intervals throughout the year. While this approach was once considered best practice, research and real-world results have shown that routine, calendar-based worming is no longer the safest or most effective way to manage parasites in horses.
Today, veterinarians and equine health experts recommend a more targeted, evidence-based approach that focuses on testing, risk assessment and pasture management. This shift aims to protect horse health while also preserving the effectiveness of worming products for the future.
Why has horse worming changed?
The biggest driver behind the change in worming advice is parasite resistance. Over time, frequent and unnecessary use of wormers has allowed some worms to survive treatment and pass on resistant traits. As a result, certain wormers are now less effective than they once were.
Regular worming without testing often treats horses that do not need it. In most herds, only a small percentage of horses are responsible for shedding the majority of worm eggs onto pasture. Treating every horse on a fixed schedule increases chemical exposure without improving parasite control.
Modern worm management
Effective parasite control is not just about using worming products — it relies on a combination of testing, targeted treatment and good management practices. One of the most important tools in modern worm control is the Faecal Egg Count (FEC).
A Faecal Egg Count is a laboratory test that measures the number of worm eggs present in a horse’s manure. It helps identify which horses are shedding higher numbers of eggs and contributing most to pasture contamination. This allows treatment to be targeted to horses that actually need it, rather than worming every horse on a fixed schedule.
FECs work best when combined with good pasture management, including regular manure removal, avoiding overstocking, rotating grazing areas, and quarantining and testing new horses before introducing them to a herd. Together, these practices reduce parasite exposure, lower reinfection rates and help maintain the long-term effectiveness of worming products.
Modern worm management is about using the right tools at the right time. By moving away from routine worming and combining faecal egg counts, targeted treatments and good pasture management, horse owners can make informed decisions that protect their horses’ health while helping ensure wormers remain effective for years to come.