Halter your horse. With an assistant at the head of your horse, stand on left side of your horse at their head, and move to their shoulder.

The area in which it is safe to give an IM injection is within a triangle located in the flat of the neck. The top margin of the triangle is a hands width down from the base of the mane. The bottom of the triangle is a hands width up from the jugular groove of the neck. The base of the triangle is parallel to the horse's bony scapula.

Once you have identified this target area with certainty, now you must carefully break this training into small steps. Keep the syringe in your pocket for now.

First, the horse must learn to accept a skin pinch. Move to the shoulder, holding the lead rope in your left hand so that you can correct the horse if it tries to evade. Pinch the skin in the injection location triangle, hold and release only if the horse accepts it and relaxes.

If the horse evades, apply the pinch with more force, and apply pressure on the halter in the amount needed to counteract the evasion. The second the horse stops the behavior, stop the pressure on the halter, and then stop the pinch. Do this until the horse stands quietly while you apply the pinch and release it. Walk the horse forward a few steps. Repeat the skin pinch. If the horse accepts it without moving, you are ready to inject.

Swab the injection site with alcohol. Remove the needle cap and keep it under the small finger of your injecting hand. Just to the side of your chosen point of needle insertion, pinch the skin tightly.

Bracing your injecting hand on the side of the neck, pass the needle through the skin, perpendicular to the skin and all the way to the hub. Pull back on plunger. If no blood is pulled back into the syringe, inject.

If blood is pulled back into the syringe – do not inject. Pull the syringe back out and redirect the needle into another area. Again, check for blood and only inject the medication if there is no blood. After the horse accepts the injection, immediately walk the horse forward a few steps and reward the behavior with a pat on the neck.

This description assumes that you are competent at giving an IM injection to a compliant horse. If you have difficulty performing this skill on a willing horse, do not attempt to perform it on a difficult or needle shy horse. If you cannot pinch skin on your horse's neck without resistance, you probably cannot safely perform this skill.

The size of the needle you choose will depend on the type and volume of medication injected. We try to use the smallest gauge needle possible. Small gauge needles create a smaller hole in the tissue and so are less painful. But the downside is that it takes a long time to push large volumes of medication through a small needle.

Handle all medications as recommended and refrigerate as directed. The rubber stopper in the neck of the bottle should be wiped clean with an alcohol swab and shaken as directed. Allow the alcohol to evaporate for a moment. If you are withdrawing more than 5 ml from a bottle, you may find it helps to inject a few ml of air into the bottle first, to reduce the vacuum.

Always identify the “target triangle” beforehand.

Always use a new sterile needle for each injection and dispose of it properly afterwards.

To ensure you do not accidentally give the injection into a vein, pull back on the syringe plunger immediately before depressing the plunger. If you see blood pulled back into the syringe, do not inject. Pull the syringe and needle out and redirect the needle into another area. Again, pull back on the plunger to check for blood and only inject the medication if there is no blood.

There are two painful parts to injection. The most painful is penetrating the skin. The second most painful is stretching the muscle with lots of medication. Use only as much volume per site as recommended.

Teach your horse to accept the skin pinch regularly, without actually injecting. Practice this on a routine basis before the need to give an IM injection arises.