Rethinking Deworming Practices
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236 – November/December, 2025
By Megan Sacia Ulrich
The American Association of Equine Practitioners (AAEP) released updated deworming guidelines last year that upends the popular practice of deworming whole herds of horses on a fixed interval each year, and also responds to the growing concern of widespread anthelmintic resistance.
According to the guidelines, the AAEP now discourages fixed-interval, year-round deworming and rotating dewormers. Their revised recommendations state that the majority of adult horses should be dewormed twice a year at most. They also advise horse owners to work with their veterinarians to conduct fecal egg count tests to identify high-shedding horses that would then be candidates for additional targeted deworming treatments. The difference is, though, that those high shedders are now the only ones receiving the extra dewormer doses, rather than the whole herd.
“The industry has seen increasing resistance levels to several parasite treatments, which can be caused, in part, by deworming too often and with active ingredients that do not target the right parasites at the right time,” said Dr. Nathan Voris, Director of Equine Technical Services at Zoetis U.S. This resistance is exacerbated by blindly deworming whole herds of horses, not knowing which horses truly need the treatment.
Click here to read the complete article
236 – November/December, 2025
