Horses Intramuscular Injections

This infomation is intended for clients that are comfortable and willing to administer intramuscular injections and have horses that are relatively well-behaved during this process.  It is only recommended to give injections under the advice of a veterinarian. If you are unsure or your horse is needle-shy, you and the vet will need to develop an appropriate plan.

Administering any type of medication to a horse by any route requires thought and attention.  Intramuscular  (“IM”) injections are no exception.  IM injections are very safe if done properly.  IM injection performed improperly can lead to serious complications.  Below are some suggestions for giving a safe IM injection. 

Sterility

Sterility is paramount in handling a needle, syringe, the bottle containing the medication, and the injection site.

• Use a new sterile needle each time. 
• Handle the needle by the hub (the plastic section) only and don’t touch the needle shaft. 
• Keep the needle capped until ready to inject. 
• Wipe off the rubber top of the medication bottle with an alcohol swab prior to inserting the needle to draw up the medication.

Drawing up the medication

After wiping the rubber top of the medication bottle with an alcohol swab

Attach the covered needle to the syringe, remove the needle cap and fill the syringe with air.  Then insert the needle into the bottle.  While tilting the bottle upside down, inject air into it to produce some back pressure, then slowly withdraw the solution into the syringe.  Fill the syringe with a few more ml than required.  Then inject that small extra fluid amount back into the bottle with any obvious air bubbles. Now you have the prescribed amount of medication in the syringe. This is all accomplished with the initial single needle stick into the inverted bottle.  Withdraw the needle from the bottle. Carefully recap the needle.

Injecting the Horse

Have the horse stand in a location where it would not hurt itself or you or damage equipment if a problem should arise.  Have another person hold the horse with a sturdy halter and rope.  The horse should be held and observed for 2 minutes after the injection for any signs of an unfavorable reaction.

There are several spots horses can be given an intramuscular injection. The most common sites are the neck muscles, pectoral muscles and rump muscles. 

1. Brush any dirt or debris off the injection site. Additionally an alcohol swab can be used to clean the injection site.
2. Just before you start detach the needle from the syringe and remove the needle cover.  Tap the area near the insertion site with your finger so to reduce the chance that the horse will react to needle insertion.  Gripping the needle hub (plastic bit), quickly plunge the needle into the muscle up to the hub.  Remember, rapid needle insertion is less painful than slow insertion. 
3. Check you are not in a blood vessel by the "Pull before you push" method. Which is: if blood appears at the needle hub, withdraw the needle and reinsert it at a different location.  Re-attach the syringe to the needle and gently withdraw the plunger a short distance.  If any blood is withdrawn into the syringe, the tip of the needle is probably in a vessel.  If this happens, partially withdraw the needle and angle it slightly before reinserting it.  You need not remove the needle completely from the skin when redirecting it.  Again gently withdraw the syringe plunger to check for blood.
4. If there is no blood at the needle hub, inject the medication very slowly.  When injecting more than 10ml, it is preferable to spread the medication into a few injection sites.  To do this, inject the first 10ml.  Rather than removing the needle completely from the skin, partially withdraw and redirect the needle and give another 10ml. Remember to “pull before you push” at each site to avoid putting medication into a vessel. Repeat this in different directions until all the medication has been given.

• Posted 12 April, 2019

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