Deworming practices have changed a lot in the past 10–15 years. The best practice for deworming horses today is “strategic deworming”, not the old “every 6–8 weeks for every horse” approach. Here’s what that means:
1. Fecal Egg Counts (FEC) First
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Do a fecal egg count test (FEC) through your vet at least once or twice a year.
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This shows how heavily a horse is shedding parasite eggs.
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Low shedders (majority of horses, ~50–70%) don’t need frequent deworming.
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High shedders (~20–30%) are the ones driving pasture contamination and need more targeted treatment.
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2. Deworming Frequency
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Most horses only need 2–3 treatments per year, not the old every-2-month routine.
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A typical plan might be:
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Spring (after fecal test): Deworm if needed based on results.
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Summer/Early Fall: Usually low risk, may not need treatment.
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Late Fall/Winter: Treat with a product that also targets bots and encysted small strongyles (e.g., moxidectin or fenbendazole).
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3. Rotation Is Not Recommended Anymore
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Constantly rotating dewormers led to parasite resistance.
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Instead, choose the right dewormer based on FEC results and only treat when necessary.
4. Product Choice
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Ivermectin and moxidectin are most effective against strongyles and bots.
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Fenbendazole or oxibendazole can still be used, but resistance is common.
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Pyrantel can be useful in some situations (e.g., tapeworm control at double dose).
5. Pasture & Management
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Pick manure regularly (daily or every few days if possible).
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Don’t overstock pastures.
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Rotate pastures or cross-graze with other species (cattle, sheep, goats) when possible.
✅ Bottom Line:
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Test before you treat.
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Target only the horses that need it.
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Use the most effective dewormer at the right time of year.
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Focus on pasture management as much as on chemical control.