A Complete Guide to Deworming a Horse

When you're looking at deworming your horse, the amount of information out there can be confusing and overwhelming. But don't worry. Below you will find not only the answers to many of your questions, but the answers will be straight forward and simple. From step-by-step instructions on 'how to administer dewormer' to a handy veterinarian secret that will improve the effectiveness of your dewormer.

Check out our selection of dewormers online here.

So let's start at the beginning, because without an understanding of worms, you may likely be treating them incorrectly.

How do horses get worms?

Horses get worms from other infected horses or pastures that are infected. It's a normal occurrence in winter when our horses are put up in the barn, or spending more time with other animals to avoid the harsh weather.

Are there different types of worms?

Yes. "Worms" is a term that is used to encompass a wide variety of parasites. Below are some of the more common worm types and how and when they are commonly contracted:

1. Tapeworms: These are the most common type. They are contracted during grazing, when the horse ingests a mite found on plants.
2. Pinworms: Eggs are picked up by horses from contaminated feed, water, bedding, and may also be present on tail wraps, grooming materials, and even fence posts and stalls.
3. Bots: Infest a horse when it licks itself; the larvae then attach to the lips and tongue and burrow into these tissues.
4. Blood worms (large and small strongyles): Ingested by horses in pastures or when grazing. Blood worm eggs hatch and the larvae climb blades of grass... and are swallowed.
5. Large round worms (ascarids): Larvae migrate into the blood vessels and are carried to the liver and lungs after being ingested while grazing. The immature worms are coughed up and swallowed, maturing in the small intestine to complete their life cycle.

Why is knowing the different types of worms important?

Not matching your dewormer with the worm type will result in ineffective treatment of your horse's worms. A dewormer can only work on the worm types that it is meant for. No one dewormer kills all types of worms; they only treat across a range of worm types. For instance, in the video below, we chose to use Zoetis' Strongid paste to inoculate Ardythe's horse because we wanted to target against large and small strongyles, pinworms and large round worms. So check the labels!

Does it matter when I treat for worms?

Yes. There are optimal, and not so optimal, times to administer wormer to your horse. You can learn all about when the best time to treat specific worm types, and when to vaccinate, by checking out A Horse's Year on Zoetis

How to administer a dewormer: Step by step

1. Buy the dewormer of your choice (our selection is here).
2. Set the dewormer plunger to correspond with your horse's weight.
3. Put the syringe towards the back of your horse's tongue.
4. Plunge.

And that ladies and gentleman is a complete guide to deworming your horse. Check out our latest N40 eMag: Equine Edition here. If you still have questions, use the form below and reach out to us. We'll work to get back to you within 24-hours.