Your Informative Guide to Deworming Horses

Deworming Horses - What You Need to Know

As a horse owner, one of your top priorities is to ensure the health and well-being of your equine best friend. Did you know that deworming your horse at the right time and with the right methods is just as important as regular grooming, exercise, and proper nutrition? Worms are a common problem in horses and can cause a range of health issues, from weight loss to colic.

Schneider's informative guide on deworming horses explains the importance of deworming and how to do it properly. This guide covers all the information you need, including the timing for deworming, types of worms to watch out for, and different deworming techniques. Let's get started!

Types of Worms

What types of worms can my horse get?

There are four main species of internal parasites that horses can get infected with, Strongyles (Red Worms or Blood Worms), Tapeworms, Ascarids (Roundworms), and Bots. Each worm is a little different in how they develop, the damage it can cause, and the time of year they are most active.

Types of Worms - Strongyles

Strongyles (Red Worms or Blood Worms)

Strongyles infect horses after a horse eats the larvae. They develop into adult parasites while they make their trek through the intestines, causing colic, enteritis, anemia, weakness, emaciation, or diarrhea.

Types of Worms - Tapeworms


Nearly all horses will be exposed to Tapeworms at some point, typically young or older horses. These infestations don’t often show any outwardly clinical signs but can cause damage to the digestive tract. They do not appear on Fecal Egg Count tests. Products such as Zimecterin Gold and EquiMax will also kill off tapeworms, making those dewormers a great option to do at least once a year, in the spring and/or fall.

Types of Worms - Ascarids

Ascarids (Roundworms)

Many young horses suffer from Roundworms as their bodies don’t always have the immunity needed to fend them off in their early life. These worms begin their life in the intestines but go exploring and find their way into the liver, lungs, and throat. Heavy loads of roundworms can cause a pot-bellied look, poor coat, weight loss, colic symptoms, and even stunt a developing horse’s growth.

Types of Worms - bots


You have likely seen these during the summer months and may not have even realized what they were. Bot eggs start out as tiny yellow dots sprinkled across your horse’s legs, chest, and neck after an adult fly lays them there. These eggs will then get ingested from a horse grooming or biting at themselves during fly season, where they eventually make their way into the stomach lining. They can stay there for 8-10 months before the larvae will pass through into manure and start the circle of life all over again.

Signs of Worms

What are the signs that my horse has worms?

Some of the most obvious signs that your horse has worms are:

  • Dull coat
  • Tail rubbing
  • Itchy skin
  • Weight loss
  • Diarrhea
  • Poor performance
  • Colic
  • Poor body condition
  • Lethargy
  • Lack of appetite
  • Pot-bellied appearance

Horses almost always have some level of internal parasites in their system, it’s just a matter of how many and how long they’ve had them before they start causing health problems.

Having your veterinarian do a physical exam along with a Fecal Egg Count and/or blood test can tell you if your horse has worms and which deworming product would be necessary to remove those worms before they cause physical harm to the horse. We always encourage you to consult with your veterinarian when it comes to the health of your horse, but rest assured following these helpful tips under your veterinarian’s guidance should have you well on your way to a healthy, parasite-free horse and farm before you know it!

Disclaimer: This helpful guide to deworming horses is for informational use to help you better understand worms and parasites in horses and how they can be managed but is not intended to treat, cure, or diagnose any medical conditions or treatments for your horse. Please consult with your veterinarian with any questions regarding your horse’s deworming program.

Physical Symptoms

It can be difficult to determine if your horse has worms, as some horses may not exhibit any noticeable symptoms. However, it’s important to keep an eye out for any physical signs that may indicate a worm issue. Some common symptoms of worms in horses include weight loss, poor coat condition, a pot-bellied appearance, diarrhea, lethargy, and colic. Additionally, if you notice your horse rubbing its tail or hindquarters against a wall or fence post, this could also be a sign of worms.

Behavioral Changes

In addition to physical symptoms, horses with worms may also display behavioral changes. Some horses may become irritable, while others may seem uninterested in eating or drinking. A horse with worms may also be more prone to colic, as well as having a decreased appetite and lethargy. Because behavioral symptoms can be subtle and harder to recognize, it’s essential that horse owners are familiar with their horse’s typical behavior. If you notice any unusual changes that may be indicative of worms, be sure to consult your veterinarian immediately.

Horse Deworming Schedule

Horse Deworming Schedule

Deworming is an essential aspect of horse health care, as parasites can cause significant harm if left untreated. These harmful organisms negatively impact your horse's digestive and immune systems, leading to a range of issues, including weight loss, lethargy, and even colic. The recommended frequency of deworming varies depending on the type of worm and the area in which your horse lives. For example, in high-risk areas, deworming is recommended every 8-12 weeks.

How often should you deworm a horse?

The frequency of deworming your horse depends on the type of worm present and the location where your horse lives. For instance, deworming every 8-12 weeks is recommended in high-risk areas, while in moderate-risk areas, every 12-16 weeks is recommended. You should avoid using the same dewormer too much, or the parasites will become resistant.

Types of dewormers and when to use them

The main type of dewormers that remove worms in horses are Febedazole, Oxibendazole, Ivermectin, Moxidectin, Pyrantel Pamoate, Pyrantel Tatrate, and Praziquantel.

There are many popular dewormers for horses on the market, while most of them come in paste form, making it easy to measure the correct dose based on the weight of your horse. After discussing with your veterinarian, you can determine which product would work best either based on Fecal Egg Count test results or the rotational schedule you choose.

Here is a breakdown of what types of dewormers work on different parasites in horses:

Generic Name Brand Name Parasite Affected
Fenbendazole Panacur, PowerPac, Safe-Guard Large and small strongyles, encysted cyathostomins, pinworms, ascarids.
Oxibendazole Anthelicide EQ Large and small strongyles, large roundworms, pinworms, and threadworms.
Ivermectin Zimecterin, Zimecterin Gold, Ivermectin, Bimectin, Ivercare, EquiMax Large and small strongyles, small bloodworms, ascarids, bots, threadworms, pinworms, hairworms, lungworms, and large mouth stomach worms.
Moxidectin Quest Gel, Quest Plus Gel Large and small strongyles, encysted cyathostomins, ascarids, hairworms, pinworms, largemouth stomach worms, bots, and tapeworms.
Pyrantel Pamoate Strongid Paste, Exodus, Pyrantel Pamoate 3.60g Large and small strongyles, pinworms, and large roundworms.
Pyrantel Tartrate Strongid C, Strongid C 2X Large and small strongyles, pinworms, hairworms, threadworms, ascarids, summer sores, bots.
Praziquantel Quest Plus Gel, Zimecterin Gold, EquiMax Large and small strongyles, ascarids, hairworms, threadworms, stomach worms, lungworms, bots, pinworms, and tapeworms.

Importance of rotating dewormers

The strategic use of different classes of dewormers in a rotation schedule can maximize effectiveness and minimize resistance. By working closely with your veterinarian, you can tailor a deworming program based on your horse's specific needs and the worm load associated with your pasture management system. With a rotational deworming schedule, you can help protect your horse's health and prevent the development of drug-resistant parasitic populations.

What is a good deworming schedule for horses?

A good deworming schedule includes rotational deworming, where you rotate the different types of dewormers to ensure you’ve covered all types of worms at the ideal times of the year. Here is a great example of a horse deworming rotation chart based on the target active ingredient in the deworming products:

When to Deworm Generic Name Brand Name
January/February Fenbendazole/Oxibendazole Panacur, Safe-Guard
March/April Ivermectin/Praziquantel Zimecterin Gold, EquiMax, Ivermectin, Quest Gel
May/June Pyrantel Pamoate Strongid Paste, Exodus, Pyrantel Pamoate 3.60g
July/August Fenbendazole/Oxibendazole Panacur, Safe-Guard
September/October Ivermectin/Praziquantel Zimecterin Gold, EquiMax, Ivermectin, Quest Gel
November/December Pyrantel Pamoate Strongid Paste, Exodus, Pyrantel Pamoate 3.60g

Combining deworming products with an effective management system around your farm can help reduce the number of worms your horse is exposed to. These are some great ways to reduce or prevent the number of parasites on your farm:

  1. Manage Pastures: Remove manure when possible, or mow/harrow pastures to break up manure piles which exposes them to predators such as birds, small mammals, or rodents. Doing this weekly can greatly decrease egg and larvae populations.
  2. Pasture Rotation: Move horses from different pastures, allow some pastures to rest for at least a few months, and try to keep the number of horses in each pasture low.
  3. Deworm Your Horses: On either a rotational program or based on annual or semi-annual Fecal Egg Count tests.

What happens if a horse is not wormed?

If your horse is not wormed, the parasites can accumulate in their digestive system and weaken their immune system, eventually causing harm. Some types of worms can leave eggs in the environment, which can then infect your horse again later on. Additionally, certain worms can cause specific problems. For example, having a lot of tapeworms can lead to colic, and not treating bot infections can result in skin irritation and stomach ulcers.

Signs of Worms

How to Deworm a Horse

Before you begin deworming your horse, you'll need to accurately weigh them and estimate the approximate amount of dewormer needed. To deworm a horse, first, find the proper dosage, then choose between administering an oral paste or powder. For oral dewormers in paste form, you can apply the tube directly into your horse's mouth. If administering orally is a challenge, use powder dewormers that can be mixed with your horse's food.

What is the best way to deworm a horse?

It is important to remember that the most effective deworming method for horses varies depending on the individual horse. It's recommended that you consult with your veterinarian to create a personalized deworming program that includes the right dosage and frequency. In addition, it can be helpful to rotate various dewormers and closely observe your horse's health in order to increase effectiveness.

Safety considerations for horse and owner when deworming

In order to use dewormers safely for horses and their owners, it's important to strictly adhere to the recommended guidelines for dosage and administration. Overdosing can lead to serious health risks and drug resistance. Accurately record all of the medication given and the dates of administration. When handling dewormer substances, wear gloves, use in a well-ventilated area, and avoid inhaling fumes.

Proper dosage amounts

Proper dosage amounts for dewormers depend on the type of dewormer, and the horse's age and weight. Pyrantel Pamoate and Ivermectin are common dewormers that require precise dosing to avoid treatment failure or toxicity. Calculate the horse's weight and follow the instructions on the product label to ensure correct administration.

Deworming is crucial for maintaining your horse's health. Follow our guide, consult your vet, and record all medication given. Watch for signs of infestation like colic, diarrhea, and weight loss, and take action with expert help if needed. Frequent deworming and good environmental management can help prevent infestations and keep your best friend healthy.