Having to give a horse a shot is not an unusual task for owners and equine aficionados. However, injecting the shot properly is necessary to avoid risk of abscess, infection or anaphylactic shock; for example, if you own a horse, you should always have epinephrine ready in case anaphylactic shock sets in. Most shots are either given intramuscularly - directly into muscle mass - or intravenously (directly into the blood stream). Intramuscular injections are the most common and safest to administer.
Typical injection sites are the side of the neck, the buttocks, the chest or the croup, which is the highest point of the hindquarters, on either side of the spine. It is important that you pick a spot where you are comfortable administering the shot. Some horses may be nervous and fidgety which may make the job more difficult. The easiest site for one who is new to giving his horse a shot is on the side of the neck. Regardless of your experience, always double check the dosage and drug before giving your horse the shot. Even if made with the best of intentions, the slightest mistake can kill your horse in minutes.
Clean your selected injection site of all loose dirt. Using a sterilized needle prior to attaching the syringe, insert the full length of the needle at an angle perpendicular to your injection site. If you see blood droplets form around the needle, pull the needle out and try again. You are ready to inject the medication when you have successfully inserted the needle without drawing blood.
First, attach the syringe and gently pull back on the plunger slightly. Blood should not be drawn back into the syringe. If it is, your needle has pierced a vein. If no blood is seen, slowly and smoothly depress the plunger until the syringe is empty of the medicine. To remove the needle, hold the syringe at its base where the needle and syringe attach. In a swift, smooth motion, pull back and remove the needle. You may want to rub the injection site a little to help with absorption of the medicine.
After the shot has been given, keep an eye on the horse for a few hours for signs of an adverse reaction. If the horse demonstrates any unusual signs, such as excessive agitation, lethargy, or sweating, immediately contact a veterinarian. Also, infection and abscess may develop over just a few hours or may take up to several days, so be mindful of the area during future interaction with your horse.