How Often Should You Worm a Horse?

There are many different theories and myths that revolve around horse deworming among horsemen and equine veterinarians. With a huge variety of different internal parasites, this whole process has gotten even more confusing. Most horse owners know the importance of deworming at regular intervals. 

Horsemen deworm the horses regularly throughout the year. Even some go as far as to overusing the deworming products.

Due to this deworming frenzy among equine owners, parasite resistance has become a significant problem. Timing is key when it comes to worming a horse. 

Every type of livestock and animal has parasites, with proper control, you can eliminate many health problems.

A proper deworming schedule keeps many health problems at bay while minimizing the risk of spreading worm contamination. Even after being aware of the dangers of gastrointestinal equine parasites, most horse owners choose to believe the myths and ignore the proper deworming process. 

How Often Should You Worm a Horse?

Internal parasites are a part of the horse’s digestive tract. Not all parasites are bad, some of them play a major role in keeping the gut healthy.

On the contrary, the overload of worms can lead to many potentially dangerous health problems. Therefore, the deworming process is quite important but the question arises that how often should you deworm a horse?

No precise horse deworming schedule exists that works for every animal in every situation or every type of worm. Traditionally, a house should be dewormed every two months.

It is suggested that rotate the deworming agents. Do not use the same deworming medication regularly, switch to others to prevent the risk of the parasites building up resistance to the chemicals.

Some adult horses develop immunity to the internal parasites and will be fine being dewormed only in the spring and fall.

However, horses with a low level of immunity need continuous deworming treatment to prevent the reintroduction of worms. 

Horse Deworming Schedule 

It makes little sense that all horses should have a similar deworming schedule. Immune horses do not shed many eggs and will stay perfectly healthy even when treated with a dewormer twice a year.

Horses less than three years old or young horses are more susceptible to parasite infection and developing parasite-related diseases. Therefore, a horse owner should set a schedule as per the horse’s deworming needs.

Horse Deworming Guidelines

You are living a dream if you believe that it is possible to get rid of all internal parasites in horses. These deworming medications can only limit the risk of parasite infection but can not eliminate it fully. Here’s are some guidelines related to deworming a horse at specific intervals.

  • Horses over the age of 3 may need more than one or two yearly treatments depending on their immunity. If the horse lives alone in a clean stable, the frequency could be less. 
  • In herds, the fecal egg count will point out the moderate and high egg shedders for deworming. Moderate and high shedders may need three to four deworming treatments a year. 
  • Low shedders and horses with a high level of immunity will only require one or two treatments at most.
  • Deworm only at the appropriate time and avoid the temperature extremes of winter or summer and during droughts. 
  • Stabled horses having less interaction with other horses require deworming infrequently. 
  • Foals should get at least 4 deworming treatments in the first year starting at the age of two or three months. 

There are no one-size-fits-all deworming programs for all horses. To properly control parasites require setting up a reasonable program and sticking with it.

Factors Affecting The Deworming Schedule

As you know by now, there can be no single deworming schedule for all horses. Different factors affect the schedule to worm the horse. 

  • Age – Young and older horses are more susceptible to parasite infection, so, they may need frequent deworming. When the horse is very young or very old, its internal resistance to contamination is weak, so, parasites are more likely to attack during these vulnerable times.
  • Health – If the horse is overall healthy or does not have any disorder or health problems, the frequency of deworming treatments would be less. They can do well with fewer deworming treatments and can naturally resist the ill effects of these internal parasites.
  • Size of Herd – If the horse is living alone in a stable or in a barn, it would need deworming less frequently. If there are multiple animals in a herd, the risk of contamination is increased significantly.
  • Pasture Condition – A dirty, small pasture can hold large concentrations of these potentially dangerous worms. Properly treat the field with effective pasture control.
  • Climate – Horses living in warmer and moist environments would need frequent deworming. Whereas, it is the opposite for horses living in a colder and drier climate. 
  • Exposure – If the horse is in contact or mingling with unfamiliar horses at shows or boarding facilities, monitor the fecal egg count and they may need frequent deworming treatments. 

Keeping The Horse Worm-Free

Setting up a proper deworming schedule can not help if you do not manage effectively the surrounding environmental factors. Take important steps to minimize worm contamination and use deworming treatments less frequently so that the parasites do not become resistant to deworming medication. 

  • Manage The Pasture – Pick up and remove the manure from the pasture to inhibit the production of larvae and eggs. Mowing pasture and harrowing the pasture exposes the manure and worms to strong sunlight and drier conditions. Rotate pasture every 6 to 8 weeks and let fewer horses graze in each field.
  • Fecal Egg Count – When the horse is showing symptoms, monitor the fecal egg count. It not only informs the owner whether a horse needs deworming or not but also the effectiveness of the deworming program.
  • Dewormers – Use different dewormer agents to prohibit the growth and multiplication of these parasites. These dewormers lessen the chance of re-infection by decreasing the number of infected larvae in the feces.

In brief, not all horses can have the same deworming schedule. It depends on different factors and environmental conditions to determine the number of deworming treatments.


Hi, I am Waqar and active in the horse world since 2012. I have MSc (Hons) in Agriculture from the University of Agriculture Faisalabad. I love to solve equine health care issues and note down in the form of research papers. I have written hundreds of equine health care, accessories, names, and history-related blogs. My equine related work is watering a lot of horse-related magazines and blogs.

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