Introduction: Vaccinating a Horse

Veterinary costs are one of the biggest expenses a horse owner incurs. Anyone who owns horses knows that saving even a small amount of money can be a blessing. Thankfully, there are a few procedures horse owners can do on their own to alleviate some veterinary costs.

Every six months, horses get a routine set of core vaccines. These vaccines include Tetanus, Eastern/Western Encephalomyelitis, and West Nile Virus. Once yearly, horses are vaccinated for Rabies. These vaccines are given via an intramuscular injection in the muscles in the base of the neck of the horse. With this tutorial, the owners can purchase their own vaccines and administer the vaccines themselves without the added costs of doctor's time or farm calls.

As a veterinary assistant with multiple years of equine experience, I am qualified to outline the correct way to vaccinate a horse. Additionally, the procedures outlined in this Instructable are applicable to any intramuscular injection. However, it is important to note that if the horse being vaccinated has any adverse side effects such as hives, fever, excessive sweating, or colic, a licensed veterinarian should be notified immediately (AAEP, 2015). Additionally, one should understand there are risks of medicating an animal with a veterinarian, and I am not held liable for any problems that may or may not arise.

Step 1: Prepare Your Needle and Syringe

A typical vaccine is given with a 20 gauge, 1 and 1/2 inch needle (shown in the first picture) and a 3 cc syringe (shown in the second picture).

Remove the cap over the back end of the needle (light pink cap in the picture above).

Remove the cap by twisting and pulling. The back opening of the needle will now be exposed.

Attach the Needle to the Syringe

If the syringe is in a casing, remove it. Then insert the end of the syringe into the exposed back of the needle. Some syringes and needles have a corkscrew and the needle must be screwed into the syringe, other needles and syringes can be attached by just pushing together. The final product is depicted by the last picture.

Step 2: Draw Up the Vaccine

Drawing up the vaccine is the act of aspirating the vaccination from the vial into the needle and syringe. If the vial is new, the first step is to remove the cap from the top of the vial. If the vial has been used before the cap will no longer be present.

After preparing the vial, locate the prepared needle and syringe and remove the cap covering the needle. Insert the needle into the center of the top of the vial by gently pushing it through the rubber seal on top. Once the needle is pushed through the rubber seal, invert the vial so it is upside down. Gently slide the needle out until the tip is covered by the liquid inside the vial. Once the tip is covered, pull back on the plunger aspirating the liquid into syringe. Fill the syringe until it passes the CC marker for the amount of serum necessary. The vial will specify how much to draw up per horse. The first picture above shows the proper way to aspirate the vaccine serum into the vial.

Once the correct amount of serum has been drawn into the syringe, it is important to remove any excess air from inside the syringe. While holding the end of the syringe with the needle pointed up, gently flick the end of the syringe closest to the needle. Any air bubbles in the serum should then rise to the top. After the air bubbles have risen to the top, gently press the plunger until the air escapes and about one drop of serum comes out of the tip of the needle, as the second picture depicts. Once the air bubbles are gone, replace the cap on the needle.

Step 3: Locate Injection Site on Horse's Neck

After the syringe has been prepared, it is time to locate where on the horse's neck to give the injection. The vaccine is injected into the muscles near the base of the horses neck. There is a triangle you can draw (pictured above) that is outline by several important structures in the horses neck that are important to avoid.

A line is drawn through the top of the horse's neck along the bottom of the Nuchal ligaments. The line down the bottom of the horse's neck runs along the top of the cervical vertebrae. These two lines will cross making the top border of the triangle. The right side of the triangle is bordered by the horse's shoulder blade. A visual depiction of this triangle is shown by the picture above (McCall, 2012).

The injection can be administered anywhere within this triangle, however injecting closer to the base of the neck by the shoulder blade, where there is more muscle mass, can help prevent some muscle soreness that may arise from the injection.

Step 4: Insert Needle

Once you have located the proper injection site, it is time to insert the needle. Choose the area of the neck within the allotted triangle where you would like to inject. Then, remove the cap from the needle. After the cap has been removed, take your non-dominant hand and pinch a small amount of skin next where you would like to inject. Then push the needle into the neck in one quick, steady motion. It is important to insert the needle perpendicular to the neck and straight into the muscle, as shown in the first picture, and not at an angle as shown in the second picture.

Step 5: Administer Injection

Once the needle is in place, pull back on the syringe. You should not be able to aspirate any liquid or blood. If you aspirate blood, it means the needle has pierced a blood vessel, and you must remove the needle and reinsert it into another place in the neck. If nothing is aspirated into the syringe, push down on the plunger with constant pressure until all of the serum has been administered into the muscle. Once the vaccine has been administered, pull the syringe and needle straight out of the horses neck and put the cap back over the needle.

If more than one vaccine is being administered, it is important to divide them equally between the two sides of the horse's neck so one side of the neck does not become drastically more sore than the other. It is also important to make a note of which vaccine is given on which side of the horse's neck in case the horse has a reaction.

Step 6: Dispose of Needle and Syringe

Once the needle and syringe have been used, it is important to dispose of them properly. Needles and syringes are single use and must be discarded so no bacteria is injected into a horse. Additionally, needles are considered biohazards and must be disposed of properly. The needle should be removed from the syringe, and placed in an allocated sharps container, such as one pictured above. If there is room, syringes can also be discarded in this container. However, syringes may also be discarded into a normal trash can.

Step 7: References

American Association of Equine Practitioners (AAEP) (2015). Vaccinations for adult horses. retrieved


McCall, C (January, 2012). How to give your horse an intramuscular injection. Alabama A&M and

Auburn Extension. retrieved from

Valley Vet Supply (2015). Equine medical supplies. retrieved from

Vorvick, Linda (July, 2015). Drawing medicine out of a vial. U.S. National Library of Medicine. Retrieved from