How to Give Your Horse an Intramuscular Injection

Last Updated on March 18, 2022 by Allison Price

Horse owners may need to inject their horses in some cases. Veterinarians are the ones who tend to give horses injections. Horse owners must be able to administer intramuscular injections safely. This article will explain the methods and locations for giving an intramuscular injection to a horse.

Horse owners may have to inject their horses from time to time. It is easy to give an injection to your horse. Your veterinarian should determine the type and dosage of medication your horse requires and the best way to administer it.

  • There are four main types of injectables that horses can use.
    • Intravenous injections are given through a vein.
    • Intradermal injections are administered to the skin.
    • Subcutaneous injections (SQ), are given under the skin.
    • Intramuscular injections (IM) are administered deep into large muscles.

These intramuscular injections are the most commonly used type of injection in horses. This article will focus on them. While some horses may be hesitant about needles and refuse to receive injections, the majority of horses will happily accept an IM injection. Horse owners should be able safely and efficiently administer an IM injection to their horse by following these steps.

Safety First

Consult Your Veterinarian!

While injecting IM to horses is a common procedure, there are still risks to their health. Before giving any medication to horses, consult your veterinarian about the type, dosage, and route (intramuscular or intravenous, subcutaneous or intradermal).

Intramuscular Injection

Incorrect drug handling and injection techniques could lead to serious drug reactions, including death. Discuss with your veterinarian the signs and treatment options for horses suffering from drug reactions.

Take Care of Handlers

The human handler may also be at risk when injecting a horse. Two people should be available to administer an injection if possible. The injection is given by one person while the other holds the horse. Horses that are hostile to injections can inflict themselves and their handlers. Some drugs used in horses can also be absorbed through the skin of humans or cause severe reactions if they are accidentally injected via needle punctures.

Ask your veterinarian for safety precautions when administering a drug or injecting.

Precautions for Medication

Before you give any injections, make sure to read the label. Before you take the medication out of the container, and before injecting it into your horse, it is a good idea to read the label. To ensure that the recommended drug name is correct, check the label. Keep in mind that the brand name and the generic name of a drug may be different.


Next, verify the recommended dosage. These may be different from what your veterinarian has recommended. Ask your veterinarian for clarification if you have questions about the dosage.

Route Of Injection

Make sure you know the best way to inject the drug. If you have any questions, consult your veterinarian.

Drug Handling And Storage

Follow the recommendations for drug storage, drug handling, expiration dates, precautions, and drug handling. Mix individual packaged drugs together in one injection. The effectiveness of one drug may be diminished or inactivated by compounding in another drug preparation. It is safer to give two injections to the horse than to be reckless.

Sterile Equipment

Make sure to use a sterilized needle and syringe. Disposable sterile needles or syringes that are individually packaged are the best way to ensure sterilization. You should open the package immediately prior to use. After use, dispose of them in a medical waste container. Reuse needles only once. A contaminated needle can quickly spread infection to horses.

Needle Size

The medication being injected will determine the size of the needle. A large-diameter needle (18 gauge), works best for thick solutions like penicillin. While a smaller needle (20-21 gauge) can handle thin, watery solutions, it is more suitable for thinner needles. A larger gauge equals a smaller diameter. A needle of a larger gauge may be more susceptible to breaking than one of a smaller gauge. If your horse reacts negatively to the injection or breaks the needle, make sure you have both ends of the needle. Your veterinarian should be consulted if you think that a part of the needle might have been retained in your horse’s muscle.

Adult horses are usually given IM shots with a 1 1/2 inch needle. This allows the medication to be injected deeply into the muscle mass. Foals usually receive IM injections using a 1-inch needle. Take out any used needles with the plastic covers still attached and place them in a plastic bag or plastic bottle. Then, take them to your veterinarian for disposal in a medical waste container.

Site preparation

Most horse owners and veterinarians don’t practice antiseptic cleaning at the injection site. The horse owners or veterinarians simply scrub the injection site and then insert the needle into the skin. This method is not as infected as the one that uses antiseptic cleaning agents.

The cleanliness of the injection site is not affected by the use of an antiseptic soap. This has been proven in studies. The horse’s hair should be shaved and the area must be scrubbed with an antiseptic soap. This soap must stay in contact with the skin for at minimum two minutes before being rinsed with alcohol. Most horse owners don’t want their horses to be shaved at the injection sites. It is better to use a sterile needle or syringe than to clean the injection site thoroughly.

Horse Handling

You can’t predict how your horse will react to injecting horse. It is best to either untie your horse and keep its lead line, or have someone else do it. If a tied horse reacts too strongly to an injection, it may pull against the tie rope. The horse may panic and become agitated from the pressure. If your horse pulls back during an injection, you can simply move along with it and continue the procedure until it calms down. Pull your horse’s head towards you if it attempts to kick. This will cause the horse’s rear end to swing away from you. For horses that are very sensitive to needles, a twitch may be necessary. This is a device that tightens the horse’s nose and upper lip. An alternative option for experienced horsemen is to tie or place a horse in stock. This is especially useful for horses who are very dangerous to inject. This method can also be discussed with your veterinarian.

Injection Sites

Safety of both the horse and the handler is paramount. You should choose a muscle mass that is active and well-used by your horse. This increases drug absorption and reduces swelling and pain at injection sites. The injection site should be able to insert the needle deep into the muscle without causing injury to bone, ligaments, or blood vessels. The injection site should be able to accommodate the horse’s objections and allow the handler to remain in a safe place.

Base of the Neck

Horse handlers love to inject horses at the base of their necks. This allows them to stay in a safe zone by the horse’s shoulder.

This area is defined by the nuchal ligaments at the horse’s neck and the cervical vertebrae, which form an S-shaped curve backwards from the point of the shoulder to the point between the horse’s ears. (See Figure 1).Figure 1. Figure 1. Muscle soreness can be prevented by staying near the base of the neck.

Place the heel of your foot on the area where the horse’s neck joins with the shoulder. This is approximately midway between the horse’s crest and the base of his neck. Your palm will cover the injection site.

You risk striking the nuchal ligaments if you go higher than the crest. The cervical vertebrae are at the bottom of your neck, so stay closer to the base. You should inject near the base of your neck, not higher towards the ears. This allows you to avoid ligaments, bone, and blood vessels. It also gives you a greater muscle mass for the injection.

Never give a nursing foal a neck injection. The foal might be reluctant to nurse if the neck is sore after the injection.

Buttocks Region

Another large muscle mass, the semitendinosus, is located below the horse’s point. It is an excellent injection site (see Figure 2). This muscle is used every step the horse takes. It is an excellent site for injecting drugs that can cause pain and swelling. Because it is one the largest muscles on a foal’s body, it is the most preferred place to inject drugs.Figure 2. Figure 2. The top border of the injection site is approximately one inch below the point at the buttocks.

This injection site has a major disadvantage. It puts the handler in the horse’s kicking zone. Only experienced horse handlers should use it. Horse handlers need to remember that horses can kick at people inflicting pain, not at the painful areas. If you are standing on the left side, and reaching across to inject the right buttock, you could be kicked. You may be kicked by the horse’s left hind leg, rather than its right.

Locate the bony protrusion at the top of your buttocks to find the injection site (tuberischii). Drop approximately 1 inch below tuber ischii, and inject anywhere along the large muscle mass at the back of your leg.

Pectoral Muscles

Another possible site for injection is the pectoral muscles at the chest (see Figure 3). The handler is at risk as the handler must be able to see the site clearly from the front. This puts the horse in an awkward position and could easily be bitten, struck with the front foot, or run over by him. Pectoral muscles can become sore quickly and should only be used when the horse has been receiving long-term treatment. This area can be drained if there is a problem.Figure 3. Figure 3. This area can cause stiffness and soreness in the horse’s muscles, which could make it unsafe for the handler.

This is the injection site for the bunchy muscles located in the lower chest between the tops and the forelegs.

Top Of The Rump

Horse handlers often inject the horse using the top of their rump (gluteal muscle mass). This large muscle mass is frequently used by horse handlers and allows them to stand in a safe place while administering the injection.

This site has a disadvantage: it is very difficult to drain if there is a need. This site is difficult to treat as an infection can spread up the back and loin. It is not recommended to inject this site. It can however be used to treat horses with severe pain or horses who are unable to use other injection sites.

This site should be located at the intersection of the points of hip and tail head.

Injection Techniques

  • There are many ways to inject IM into horses. The horse’s attitude, your experience and the location where the injection is given will determine the method you choose. No matter what injection method you choose, there are some basic rules that you should follow.
    • Place the needle parallel to the skin. Do not tilt upwards or downwards. The needle should be inserted into the muscle until it reaches the hub. This will ensure that the needle does not move during injection, and that it is firmly inserted into the muscle.
  • To ensure you aren’t in a blood vessel, always pull back on your plunger before injecting any drug. Inadvertent injections of common drugs into the bloodstream can cause death in horses.
    • You must remove the needle from the horse if blood is collected at the tip of the needle. It is safer to remove the entire needle and then start again with a new needle.
    • If your horse is not comfortable with needles, you can pull it out of the muscle. Many horses that are afraid of needles will object to the needle being inserted through their skin. This is the most painful part of the procedure. Once the needle is through the skin, they will be quiet. Make sure to aspirate once more if you use a clean needle, or redirect a needle, to ensure that you are not in any blood vessels.
  • You need to insert the needle quickly and clearly. It is quicker for you to stab the horse quickly than if you wait to insert the needle into the skin.
  • You should be prepared for adverse drug reactions. Anaphylactic shock can occur quickly and horses may die in a matter of minutes. Talk to your veterinarian about signs and how to treat anaphylactic shock. In the event of an allergic reaction, your veterinarian may give you epinephrine. When you give injections, make sure to have the epinephrine ready. The horse could die if you have to take the epinephrine to another place. Be safe and keep others safe. Horses with drug reactions can be dangerous and unwise to approach.
  • After the injection, observe the horse closely for signs of an allergic reaction. The usual signs of an allergic reaction include swelling at the injection site, hives and increased respiratory rate. Stop using it and immediately consult your veterinarian.
  • To reduce the soreness in any area of the horse’s skin, rotate injection sites (left neck/right neck, left buttock/right buttock) if you are administering large and repeated doses. To reduce the soreness, you should not give excessively large doses (more than 15 to 20 cc) of an irritating or thick substance like penicillin.
    • When administering multiple medications or vaccines simultaneously, it is a good idea to use more than one injection site (e.g. the neck and buttocks). It may also be easier to identify the drug responsible if the horse experiences a drug reaction.

IM Injection Procedure

  • To inject IM, the general procedure is as follows:
    • Take the needle out of the syringe.
    • Put the needle in the muscle
    • Attach the syringe
    • Aspiration, and
    • Slowly insert the medication.

Many novice horse owners worry about injecting air into their horses if the needle is not attached to the syringe. This amount of air is not harmful to the horse and it will not be dangerous.

You may be able to just stick the needle in the neck or buttocks of a calm horse. There are many ways to make the needle stick more comfortable for horses that need distraction. A good way to distract the horse is to pinch the horse’s skin near the injection site, for a few seconds (see Figure 5). Hold the pinched skin in your hand and insert the needle near the pinched area.Figure 5. Figure 5.

You can also hold the needle between your thumb and forefinger. Tap the horse vigorously with your palm at the injection site. Next, rotate your hand to insert the needle. Some horses may associate taps with the next needle stick, and will leave the area before the needle stick. The tapping technique can also be used to inject drugs in the neck. Horses may become more responsive to hand movements around the neck and head.Figure 6. Figure 6.

Similar methods include rubbing the horse’s hair in the same direction several times and holding the needle between your thumb and forefinger. The needle should be inserted on the final rub.


It is easy to give your horse an IM shot. You can avoid serious side effects and infections by following safety procedures. Below is a summary of the IM injection process.

  1. Discuss with your veterinarian the drug type, route of administration, dosage and precautions.
  2. Refer to the label.
  3. Only use sterile needles or syringes
  4. If you are unsure of the horse’s reaction, untie it.
  5. The needle should be inserted straight into the muscle, and then up to the hub.
  6. Attach the syringe and needle.
  7. Pull back (aspirate) the plunger. If there is any blood in the syringe you can remove it and replace it with a new one.
  8. Slowly inject the medication.
  9. Watch out for signs of an adverse drug reaction in horses. In case of anaphylactic shock, make sure that you have epinephrine available for injection.
  10. You should properly dispose of your needles and syringes in a container for medical waste.
Allison Price
Allison Price

I’m Allison, born and raised in San Diego California, the earliest memory I have with horses was at my grandfather’s farm. I used to sit at the stable as a kid and hang out with my Papa while he was training the horses. When I was invited to watch a horse riding competition, I got so fascinated with riding!