Is Rotational Worming Horses the Best? Find Out

What is the Best Equine Worming Rotation Schedule for Your Horse?

As some strains of parasites grow resistant to certain types of wormers, the rotational worming discussion has turned into a full-blown debate.

In this article we will provide some of the benefits and consequences of rotational worming horses as well as a couple of non-chemical methods to prevent parasites.

Wormers have been used for quite some time now, so its no surprise that some wormers are losing their effectiveness in certain areas.

Latest Spinning-Related Articles

ALSO SEE: Why Do Horses need Bell Boots?

Horse’s host thousands of parasites, but not all of these are harmful. There are about 10 categories of worms that horse owners really have to worry about.

The most prominent categories in North America are:

Ascarids (or Roundworms)

It affect foals and yearling more than mature horses.

Most adult horses are able to develop a resistance to these parasites.

Symptoms of Ascarids may include:

  • looking pot-bellied,
  • lack of growth,
  • diarrhea,
  • and chronic coughing


These parasites are able to affect horses of all ages by attaching eggs to the horse’s hair.

When the horse licks the eggs they attach to the tongue and migrate to the stomach.

Bots don’t cause major digestive respiratory or digestive issues, but you can tell if your horses are affected by the eggs laid on their coat.

Large Strongyles

Possibly the most dangerous of parasites, Large Strongyles have the ability to do irreparable damage to arterial walls.

Unlike other parasites, horses are not able to develop any immunity as they age.


These worms affect foals as young as four days old by ingesting them through the mare’s milk.

Symptoms include:

  • diarhea,
  • and weakness


Pinworms are relatively harmless compared to other parasites.

These parasites are also easily killed by conventional wormers.

Symptoms include:

  • Intense itching of the tail

Ivermectin Paste Buy It Here!

Contrary to popular belief, worming every other month is not the best option for every horse.

To determine your horse’s schedule you should first get an egg fecal count according to a new study conducted by Colorado State University.

Is Rotational Worming Horses Best

By doing this you can group your horse into one of these horse worming schedules.

Horses that have less than 200 eggs per gram of manure should be wormed as follows:

  • Spring- (around march) with Ivermectin (this includes brands Equell, Zimectrin, Ivercare, and Rotectrin)
  • Fall- (around October) with ivermectin w/praziquantel (this includes brands Equimax and Zimectrin Gold)

Horses that have between 200 and 500 eggs per gram of manure should be wormed as follows:

  • Spring- (around March) with a wormer containing active ingredients ivermectin, moxidectin or double-dose fwenbendazole for five days.
  • Summer- (around July) with active ingredients pyrantel pamoate, fenbendazole.
  • Early Winter- (around November) with active ingredients ivermectin w/ praziquantel or moxidectin with praziquantel.

Horses that have more than 500 eggs per gram of manure should be wormed as follows:

  • Spring -(around March) with active ingredient ivermectin, moxidectin, or a double-dose of fenbendazole for five days
  • Summer- (around June) with active ingredient pyrantel pamoate, fenbendazole or Oxibendazole
  • Fall- (around September) with active ingredients ivermectin w/praziquantel or moxidectin with praziquantel
  • Winter- (around December) with active ingredients pyrantel pamoate, fenbendazole or Oxibendazole

Panacur (fenbendazole) paste Buy It Here!

ALSO SEE: Can Horses eat Avocado Leaves?

Some of the most effective techniques for managing parasites are natural methods that reduce the exposure to your horse. These include

  • Creating a manure compost pile and picking your pastures.
  • If your acreage is to great for this chore harrowing the land is also beneficial by breaking up the manure piles and exposing the parasite eggs to the elements.
  • Cross-grazing with sheep or cattle is also a great way to minimize parasite exposure because of the few number of parasites that are able to inhabit sheep and cattle as well as horses
  • Lastly, alternating your mare and foal pasture helps protect against the inhabitation of ascarids.

Zimectrin (Ivermectin and Praziquantel) paste Buy It Here!

Please leave any questions concerning the Equine worming rotation schedule, and we will be happy to respond.