It’s hard to tell who dreads deworming more, the horse or the handler. Thankfully, we have progressed from the days of having the vet come out and pass a tube into a horse’s stomach to administer deworming liquid. Unfortunately, even with the convenience of paste dewormers, some horses still view the process of administering oral medications as a perfect opportunity to test their owners’ dexterity, handling skills and patience.

It can be very helpful to practice giving medications such as dewormers, also known as anthelmintics, which usually come as a paste or gel that are administered directly by mouth, from time to time. Doing a test run using something tasty before your scheduled deworming day is a good idea, even if your horse has been well-behaved in the past.

Horses are quick learners and it may only take a time or two of having an unpleasant substance squirted into his mouth before your horse morphs into a high-headed giraffe or uses his head as a wrecking ball when he sees you approach with a tube of dewormer.

Practicing the following steps with a variety of tasty treats rather than the oral medications will quickly help turn the process into a positive experience. Fill an empty syringe with molasses, honey, corn syrup, applesauce, strawberry syrup, mashed cooked carrots, crushed peppermints in plain no-fat yogurt or baby food. Whatever you choose, a thick and sweet substance is usually best. When the time comes to administer actual medication, your horse will chalk up the unpleasant taste to one bad experience among many delicious ones.

Depending on your horse and your comfort level, having an experienced handler to assist during administration of the medication is both helpful and builds in an extra measure of safety. A resistant horse can be dangerous and with the help of someone knowledgeable, the likelihood of sustaining an injury is greatly reduced. Always be aware of where your feet are and never stand directly in front of the horse; a resistant horse could easily hit you in the face with its head or strike forward with a front foot.


1. Set the dial on the dewormer tube to reflect the horse’s weight. A weight tape can provide a fairly accurate estimate. Some deworming products, such as Moxidectin, can be toxic if given in excess – more is not always better. Always carefully read the label and instructions before administering.

2. Before giving the dewormer, ensure that the horse has an empty mouth. It is very frustrating to administer the medication only to have your horse spit it all out with a wad of feed. It is often easiest to deworm first thing in the morning when the horse’s mouth is free of hay or grain.

3. Stand on the horse’s left side, facing the same direction as him. (Note: if you are dominantly right handed, you can administer the dewormer from the right side of the horse. Some horses do not, however, like to be handled from the right, as they are not used to being worked on the off side.)

4. Reach under the horse’s head and place your right hand over his nose.

5. Hold the dewormer tube in your left hand.

6. Using your left thumb or index finger, gently part the corner of the lips and insert your finger into the mouth. There are no teeth in this area of the mouth, but be sure not to put your finger too far back towards the cheek teeth.

7. This is usually when the horse will become resistant. Follow the horse’s head movement, as most horses will resist when restrained. You may need to repeat steps six and seven a few times until he relaxes.

8. Once the horse has settled, use your finger as a guide and slide the syringe into his mouth on top of the tongue.

9. Once the syringe is inserted and pointing towards the back of the mouth, depress the plunger. Try to avoid poking the roof of the mouth with the end of the syringe and do not let the horse grab the syringe with his cheek teeth.

10. Stimulate the horse’s swallowing reflex by “tickling” the tongue with small movements of the syringe.

11. Hold the horse’s head slightly elevated with your right arm under the muzzle until he swallows.

12. Watch for a good swallow or two. If the horse is still not swallowing you can use your finger to again stimulate the tongue or rub under the throatlatch area.

Alternate Methods to Administer Oral Medications

Some horses do not like having a hand placed over their nose. If this is the case, use your right hand and lift the horse’s head slightly by placing your hand under his jaw. You can use your right thumb to part the lips and then insert the tube with your left hand. I find this method works well with even the most stubborn and resistant horse.

Other Oral Medications

In addition to dewormers, certain antibiotics, anti-inflammatories and anti-ulcer medications are administered orally. Many of these medications come in powder or pill form. Unfortunately, most horses will not readily consume these medications in their feed. Your vet will instruct you on the proper administration method when dispensing the medication and you should follow these instructions carefully. Some products cannot be crushed or dissolved and others may be toxic to humans and may require special handling.

If the medication can be dissolved in water, it is usually best to begin by crushing the tablets. A mortar and pestle works well, but you may want to invest in a dedicated coffee grinder for the job. Another method is to fold a piece of paper and place it in a sealable plastic bag. Insert the tablets between the paper sheets, close the bag and use a hammer to crush them. If you do not use the paper, the sharp edges of the pills will make tiny holes in the bag.

There are a variety of syringes suitable for administering oral medications to horses. A catheter tip or dosing syringe have long wide tips. These syringes usually hold 60ml of fluid, which is about the maximum that an adult horse’s mouth will easily hold. You can also make a dosing syringe by cutting of the tip of any size syringe, widening the hole and then smoothing the edges. Balling guns or pill guns are not normally recommended as they can cause significant trauma if the horse throws its head around.

Once the medication is in a powder format and you have your syringe, you are ready to add the liquid. The goal is to make a paste that can easily be dispensed through the tip of the syringe without being so thin that it runs out of your horse’s mouth. I usually add a small amount of water and mix thoroughly. I then add one of the yummy substances mentioned earlier to help hide the unpleasant taste of the medication. Once prepared, follow the steps above to administer the oral medication.

Potential Complications

As with any medication, you must be aware of the potential complications you could face.

Aspiration of the medication into the lungs can occur if your horse has a problem swallowing or if the horse’s head is held too high while the medication is given at the back of the throat. This is usually not an issue with short syringes, but it is important to always be attentive to your horse’s head position.

Never give oils by syringe as some oils, such as mineral oil, can cause severe damage to the lungs or even death if administered into the trachea (wind pipe). If your horse spits out the medication, contact your vet before giving a second dose as some medications may be toxic if given in excess. Your vet will decide if you should immediately give another dose or if you should wait until the next scheduled time depending on the medication and condition you are treating.

Administering oral medications can be extremely frustrating for both you and your horse. By following the above instructions and practicing with some tasty treats, it is my hope that your deworming experience will be as stress-free as possible.


I always recommend that horses have a fecal egg count done prior to deworming, as this provides an opportunity to tailor a deworming program for each horse. With the alarming problem of resistance to anthelmintics on the rise, it is more important than ever to administer dewormers only when needed.

If you are performing a fecal egg count reduction test to monitor for dewormer resistance on your farm, it is very important to take the first fecal sample before you administer the product. To collect a sample, use a sealable baggie and pick up at least three to four manure balls. Do not forget to label the bag with the horse’s name. If you are not immediately giving the sample to a veterinarian, it should be stored in a cool place.