Deworming Programs and Schedules for Horses

Last Updated on December 3, 2021

Especially for first-time horse owners, the practice of deworming can be confusing and frustrating! How often do you need to deworm your horse? What us your horse worming schedule? What’s the difference between different types of dewormers? How do horses even get worms? 

It can all be overwhelming if it hasn’t been properly explained to you.  In this article, I hope to do exactly that. I’ll be discussing why horses need to be dewormed, what the different strands of equine-effecting worms are, which dewormers are used to prevent which kinds of worms, and what standardized deworming schedules for horses are.

Horse Worming Schedule: Why Deworm?

All horses need to be regularly dewormed to maintain their health.  It is one of the most critical aspects of horse care for horse owners to understand.  Most horse owners are well versed in deworming schedules, but for beginners, it can be daunting.

Horses spend lots of time outside, eat food off the ground, and in general, do lots of things. That could expose them to parasites and/or parasitic eggs of equine-effective worms.  Moreover, horses that develop worms have these parasites inside of their bodies.

Horse Worming Schedule: Why Deworm?

Horses that have worms can develop any number of health issues.  Some of these include gastrointestinal discomfort, loss of weight, loss of appetite, loss of muscle mass, diarrhea, and colic.  Horses with worms are typically characterized by a dull, clumpy coat that struggles to shed out.

Deworming prevents this.  Dewormers flush your horse of any parasites or parasitic eggs that may be present in or on their bodies.  Thankfully dewormers have an extremely high success weight; meaning that, as long as your horse is on a proper deworming schedule, he will not get worms.

Horse Worming Schedule: Types of Worms

There are four primary types of worms that affect equines: tapeworms, bots, ascarids, and strongyles.  Each different type of worm manifests itself differently within a horse’s body. Even so, the outward symptoms of an infected horse remain the same.

Tapeworms are carried by “forage mites” which are present both in hay and in the grass.  Horses pick up forage mites while eating, and in turn, are infected with tapeworms. Tapeworms make their home in a horse’s intestinal tract and will stay there unless flushed out by dewormers.


Bots come from flies laying their eggs on a horse’s coat.  If a horse cleans its coat or cleans another horse’s coat where these eggs are, bots then enter the horse’s system.  Bots also hatch and develop in the horse’s digestive organs, commonly the stomach.

Ascarids are commonly known as roundworms. They are commonly caught by horses under a year and a half old, as their immune systems aren’t quite at full strength.  Roundworms can cause serious detriments to a young horse’s health and growth if not treated properly.

Strongyles infect horses when they ingest larvae.  Strongyles also develop into parasites in the horse’s intestinal tract.  Different species of strongyles can cause horses to colic, lose weight, and have serious diarrhea.

Horse Worming Schedule: Types of Dewormers

There are many different kinds of dewormers, all with relatively complicated names.  Some of these names include Fenbendazole, Oxibendazole, Ivermectin, Moxidectin, Pyrantel Pamoate, Pyrantel Tartrate, and Praziquantel. 

Each one of these wormers attacks different strings of worms.  Sometimes they encompass more than one category of worms. For example, Strongyles are covered by each of the above-listed kinds of dewormers.


Ascarids (roundworms) are covered by Oxibendazole and Pyrantel Pamoate. Bots are covered by Ivermectin, Moxidectin, Pyrantel Tatrate, and Praziquantel. Tapeworms are covered by Praziquantel.

All of these types of dewormers are manufactured by different companies, which also go under different names.  Every tube of over-the-counter dewormer will detail what type of dewormer it contains, typically on the label sticker.

Dewormer can typically be purchased over-the-counter at your local feed shop or farm supply store.

Deworming Schedules

So, what do you do with all of this information? How do you create a schedule that gives your horse the protection that he needs? Thankfully, the experts have created schedules that do this for us.

The below link is to a study done by the Colorado State University that details deworming guidelines for different types of horses.  It shows that different types and quantities of dewormers are needed for different types of horses.

For example, it details different deworming schedules for pregnant mares, foals, and standard adult horses.  It details how frequently different dewormers should be used so that you can create your own schedule, depending on what type of horse you have, and when you’re beginning your schedule. Here’s the link to the Colorado State University Deworming Schedule.

Above all else when creating a deworming schedule, please consult your vet.  Your vet should be your first go-to resource on all equine medical topics. Discuss worming schedules with your vet before you give your horse any kind of over-the-counter dewormer.

Some vets include route deworming in their standard visits which, frequently, horse owners aren’t even aware of.  You don’t want to give your horse over-the-counter dewormer if your vet gave him the same dewormer on his visit two weeks ago.

Yes, do your research, and have a deworming game plan ready if necessary.  But ALWAYS consult with your vet about deworming before starting it on your own.


Deworming is a crucial aspect of horse ownership.  If you don’t know how to properly deworm your horse, you’re subjecting him to unnecessary discomfort and potential long-term health issues.

Deworming helps keep a horse healthy, happy, and comfortable.  Stay educated, and always consult with your vet when you have questions about deworming, or about other equine health topics.

I hope this article helped you better understand the deworming process and the formation of deworming schedules! If so, please share this article, and share with us your experiences deworming horses, and creating deworming schedules for horses!


What is a deworming schedule?

A deworming schedule is a plan that horse owners use to deworm their horses. There are many different types of dewormers available, so it is important to create a schedule that will work best for your horse.
There are several factors that you should consider when creating a deworming schedule. The first factor is the age of your horse. For example, foals should be dewormed every month until they are six months old, but after that, they can go two to three months without being dewormed again.
Another factor is the type of dewormer you use. Some work for a specific amount of time and then stop working, while others last for years.
Last, you should consider your horse's internal parasites and the location where you live. For example, if your horse is in a high-risk area or has a higher chance of being exposed to worms, then you should develop a plan that involves more frequent deworming.

What time of year do you deworm horses?

Most people deworm their horses in the spring and fall. They deworm their horses in the spring because worms breed when it is warmer outside. You deworm your horse in the fall to kill off the newly-hatched, developing worms before they lay eggs that will hatch throughout winter.
There are some dewormers that can be given all year long. However, it is still a good idea to deworm your horse twice a year with an effective dewormer. Doing so will help to keep your horse healthy and free of parasites.

What are the benefits of deworming horses?

There are many benefits to deworming horses. Worms can cause a lot of damage to a horse in a short amount of time. They can eat away at the lining in a horse's stomach, which can lead to ulcers and colic. They can also cause a horse to lose weight, become anemic, and have difficulty breathing.
In addition, worms can lay eggs in the manure, which leads to reinfestation. This means that if you don't deworm your horse, the worms will continue to multiply and will infect your horse again.
Deworming your horse helps to prevent all of these problems. It also keeps your horse healthy and free of parasites. In addition, deworming can help to improve your horse's performance. A healthy horse is a happy horse!

What are the signs of worms in horses?

There are many signs of worms in horses. Some worms, like roundworms, are very noticeable because they come out in manure. Other worms can be detected with an internal parasite exam or faecal analysis.
One of the most severe signs that a horse has worms is weight loss. Similar to people who have worms, horses lack an appetite when worms are present. Some worms can actually cause colic, which is painful for the horse. Other worms can make it more difficult for a horse to breathe by causing damage or inflammation in his lungs.
Animals that have worms may also act differently than they normally would. They may be nervous and irritable. It may be harder to work with them, and they may not respond well.
If you suspect that your horse has worms, it is important to take him to the veterinarian for a check-up. The veterinarian will be able to tell you what type of worms are present and will prescribe the appropriate treatment.