How often can ivermectin be given to horses for parasite control according to the FDA in 2025?
Executive summary
The FDA-approved dose for equine ivermectin products is 200 micrograms per kilogram (0.2 mg/kg), commonly reported as 91 mcg per pound; labels state a single oral paste dose at that rate [1] [2]. Available sources describe dosing amount and that foals "should be treated initially at 6 to 8 weeks of age, and routine treatment repeated as appropriate," but do not specify a single, universal FDA rule for exact repeat-interval frequency — they instead instruct veterinarians to create a parasite-control program tailored to each horse [3] [1].
1. What the FDA‑approved labels say about dose — the hard number
Label information for FDA‑approved equine ivermectin pastes and liquids consistently lists the recommended dose as 200 µg/kg (0.2 mg/kg), which is presented on U.S. product labels as 91 mcg per pound; each syringe is calibrated to deliver that single dose [1] [2] [4].
2. What labels say about how often to give it — veterinary guidance, not a fixed schedule
Manufacturers’ FDA‑approved labels emphasize inclusion in “a regular parasite control program” and tell owners to “consult your veterinarian for a control program to meet your specific needs.” Foals have an initial treatment recommendation (6–8 weeks) with “routine treatment repeated as appropriate,” but labels stop short of prescribing a single universal retreatment interval for all horses — control frequency is left to veterinary judgment [3] [1].
3. Why the labels avoid a one‑size‑fits‑all frequency
Parasite burdens, local parasite ecology, horse age, pasture management, and resistance patterns affect how often deworming is appropriate; labels therefore provide the dose and approved indications and direct clinicians to tailor timing rather than mandate a fixed repeat interval. The product approvals and Freedom of Information documents focus on efficacy and safety at the single‑dose level [4] [1].
4. What product pages and veterinary resources repeat — common practice vs. label text
Retail/manufacturer pages and veterinary summaries echo the FDA dose (91 mcg/lb or 200 µg/kg) and emphasize that products control a broad spectrum of equine parasites. These sources reinforce that ivermectin “effectively controls gastrointestinal nematodes and bots” when used at the labeled dose, and they reiterate that treatment should follow an overall parasite control plan devised with a veterinarian [5] [6] [7].
5. What is not stated in current reporting — fixed retreatment intervals and human‑use cautions
Available sources do not provide a single FDA‑mandated repeat interval such as “every X weeks.” They also do not give an FDA endorsement for ivermectin use in humans for COVID‑19 — the FDA has explicitly said ivermectin is not authorized or approved for COVID‑19 in humans or animals beyond its labeled indications [8]. The labels likewise do not set blanket timing because they direct practitioners to design programs based on individual needs [3] [1].
6. Practical implications for horse owners and vets
Clinically, owners should dose at the labeled amount (200 µg/kg, i.e., 91 mcg/lb) and then follow a veterinarian’s parasite‑control schedule. That schedule may include seasonal timing, fecal egg count‑based decisions, and other drug classes (labels explicitly recommend consulting a veterinarian and highlight foal initial timing) [3] [1].
7. Competing perspectives and hidden agendas to watch
Commercial product pages and summaries (manufacturers, retailers) stress the product’s breadth and convenience; they have an implicit sales interest in encouraging use [5] [7]. Independent guidance from veterinary parasitologists and integrated parasite‑management advocates often favors targeted, evidence‑based deworming (fecal egg count–guided) to slow resistance — but such nuanced program details are not in the provided label excerpts (available sources do not mention specific resistance‑management schedules).
Summary action: dose at 200 µg/kg (91 mcg/lb) per the label, then consult your veterinarian to set the actual retreatment intervals and an overall parasite‑control plan [1] [3].