Strategic deworming in horses shifts focus to testing, not rotation

A strategic deworming approach for horses is increasingly centered on fecal egg counts, not calendar-based rotation. The core shift is away from deworming every horse on fixed intervals and toward testing horses once or twice a year, identifying low-, medium-, and high-shedders, and using fecal egg count reduction tests to confirm whether a dewormer is still working on a given farm or in a given barn. That direction is reinforced by the American Association of Equine Practitioners’ updated Internal Parasite Control Guidelines from May 2024, which advise veterinarians to stop blind rotational deworming and fixed every-other-month treatment schedules. (aaep.org)

Why it matters: For equine veterinarians, the practical issue is resistance. AAEP says dewormer efficacy should be checked annually with fecal egg count reduction testing, and mature horses generally need a baseline of one or two treatments per year, with added treatment focused on high strongyle shedders. The guidance also draws an important distinction by age: selective treatment based on fecal egg counts is not recommended for foals and young horses, where ascarids remain a primary concern and macrocyclic lactone resistance should be assumed unless testing shows otherwise. (aaep.org)

What to watch: Expect more equine practices to formalize herd- or barn-level parasite surveillance programs, especially as resistance monitoring becomes a more routine part of preventive care. (aaep.org)