Equine deworming is one of the most routine — and least clearly understood — duties of a horse owner. Again and again, we hear questions like, “How often should I deworm?” and “Can I deworm too much?”
We live in a climate that’s kind to parasites. Temperatures in the Willamette Valley do not get hot enough or cold enough for long enough to kill the parasites that shed eggs into the manure of your horses. That means, if you spread manure on your pastures, it must first be composted to kill parasites in their various stages.
But the most important step you can take is to follow a schedule that removes the parasites from all of your horses, breaking the worm’s life cycle. The parasite population on your property will then decrease, gradually, over time.
To help make this easier, and to put your mind at ease, we recommend that all horse owners, regardless of herd size, adopt a strategic deworming plan. It can be a bit complicated, but it’s manageable, and it’s important. Here’s an overview of what’s required.
Eighty percent of adult horses — yes, four out of five — should be dewormed twice a year, for tapeworm and other parasites. And the other twenty percent? They should be dewormed more frequently. We can help you determine which group your horse or horses fall into with a Preventive Parasite Screen — a microscopic exam of their manure.
If, based on that exam, your horse is in the:
- 80% group — Deworm twice a year, once in the spring with ivermectin/praziquantel (Equimax) and once in the fall with moxidectin/praziquantel (Quest Plus).
- 20% group — We’ll design a customized plan to help get the parasites under control. Your plan may require more frequent deworming and include different deworming products.
Deworming for Foals
- At three months, a double dose of Panacur
- At six months – Ivermectin
- At nine months a fecal and/or a double dose of Panacur
- At twelve months – Equimax
Why a Strategic Deworming Program?
A test-based deworming strategy:
- protects the horse’s overall health.
- identifies and targets the specific parasites present.
- eliminates over-treating.
- uncovers the egg shedders in your herd.
- helps control the drug-resistant parasite population.
But My Horse’s Poop Was Egg-Free!
A negative fecal exam does not mean your horse is worm-free. Tapeworm eggs are shed intermittently so they rarely show up in the manure. Tapeworm infestations are a common cause of mild colic. The encysted, small strongyle is a larval stage worm that doesn’t produce eggs, but it will eventually develop into an adult and begin active egg production.
mean your horse is worm-free.
First and foremost, a customized deworming program is best for your horse. It subjects the horse to deworming only when it’s needed. And it rids your horse of all parasites by incorporating a targeted selection of dewormers with different effects.
It does take commitment and good communication to make this work. You must keep this on your calendar; and it’s extra work to bring in the fecal samples for testing, especially if you have several horses. But remember this:
A strategic equine deworming program results in healthier horses. It exposes your horse to fewer medications and eliminates money spent on unneeded dewormers. And it brings you some priceless peace of mind.