Deworming schedules used to be simple: rotate dewormers every 8 weeks and call it done. That advice is outdated, and following it can actually make parasite resistance worse over time. Here's what we tell customers across our Oklahoma locations today.
Why the Old "Rotate Every 8 Weeks" Advice Changed
Years of routine, calendar-based deworming led to widespread parasite resistance to dewormer classes across the horse population. The current best practice — backed by equine veterinarians and parasitologists — is targeted deworming based on fecal egg counts, not a fixed rotation schedule.
The idea is simple: not every horse carries the same parasite load. Some horses are naturally low shedders and barely need deworming at all, while others are high shedders who need more frequent treatment. Treating every horse the same wastes money and accelerates resistance.
What a Fecal Egg Count Tells You
A fecal egg count (FEC) is a simple test, usually run by your vet, that measures how many parasite eggs are present in a sample of your horse's manure. Based on the result, horses are generally categorized as:
- Low shedders — may only need deworming once or twice a year
- Moderate shedders — typically dewormed two to three times a year
- High shedders — may need more frequent treatment and closer monitoring
Testing once or twice a year, ideally in spring and fall, gives you a much clearer picture than guessing on a calendar schedule.
Oklahoma-Specific Considerations
Climate affects parasite life cycles. Oklahoma's hot summers and mild winters create conditions where parasite larvae can survive on pasture for a good part of the year, which makes pasture management — picking up manure regularly, avoiding overgrazing, and not overstocking pastures — just as important as the dewormer itself.
Tapeworms and bots are also a consideration in our region, typically addressed with a targeted treatment in late fall after the first hard freeze, when bot fly activity has stopped.
A General Framework (Talk to Your Vet First)
While every horse's plan should be based on their own fecal egg count results and your vet's recommendation, a general framework many Oklahoma horse owners follow looks like:
- Spring: fecal egg count, followed by targeted treatment based on results
- Fall: fecal egg count, plus a treatment effective against tapeworms and bots after first frost
- Additional treatments: based on shedder status and your vet's guidance
This is general information, not a substitute for an actual veterinary parasite management plan — your vet can run the fecal testing and tell you exactly what your horse needs.
Where to Buy Dewormers in Oklahoma
Once you and your vet have a plan, we carry a full range of equine dewormers at all four Cook Feed & Outdoor locations across the OKC metro. Browse our equine dewormer collection online, or stop by any of our Oklahoma City, Yukon, Norman, or Remington Park locations.