While many horse owners opt to have a veterinarian administer vaccinations during an annual checkup, you can do it yourself, if you prefer.

Equine vaccinations can be picked up at any veterinary pharmacy – you don’t need a prior veterinary-client-patient relationship (VCPR) to purchase them. The rabies vaccine is one exception to this rule. Rabies is a reportable disease under Canada’s Health of Animals Act, so it needs to be administered by a licensed vet and properly recorded to ensure there’s proof the horse received it.

For penicillin and other antibiotic drugs, you will need a prescription from a vet who knows your horse, with whom you have an established VCPR, as per new regulations, introduced December 1, 2018, in Canada.

Giving your horse an intramuscular (IM) injection can be daunting, but it’s a useful skill to have. Whether you’re administering vaccinations or drugs prescribed by your vet, IM injections are generally easy and safe, as long as you follow a few simple guidelines.

Two areas on the horse are recommended for giving IM injections: the neck and the hamstring muscles on either side of the tail. These sites are ideal because they’re both large muscle masses as well as high-motion areas. As the drug or vaccine disperses, there’s less opportunity for pain and swelling.

The easiest area to access is the neck. Look for a triangular area bordered by the nuchal ligament (along the top of the horse’s neck), the cervical vertebrae along the bottom of the triangle and the horse’s shoulder blade at the back.

The other location that is recommended for larger volumes or repeated injections is the semitendinosus and semimembranosus muscles in the hind end, commonly called the hamstring muscles. These muscles start below the point of the buttock (ischiatic tuber) and run down to where they converge into a tendon, which is quite visible since the muscles are so big. You can inject anywhere along that muscle belly (fat part of the muscle) that runs alongside the tail.

One site that is not recommended for injections is the top of the horse’s hindquarters. If you’re giving repeated injections and the horse is very sore in other areas, you can use this muscle. But if an injection site happens to get infected and becomes abscessed, it’s in a very bad spot for drainage.

Note that when antibiotics have been prescribed, it usually means a large volume of liquid must be injected once or twice a day for several days. You need to rotate between each quarter of the horse to vary your injection sites as much as possible, and monitor the areas for any type of reaction.

Horse owners should never attempt to administer intravenous (IV) injections. Medications such as phenylbutazone (a nonsteroidal anti-inflammatory drug) or other painkilling drugs that are meant to be given as an IV injection can cause significant damage if injected into the muscle or an artery. Many of these drugs are quite irritating; they can cause necrosis (tissue death) and other large tissue defects. Horse owners are usually able to purchase these drugs as an oral dose under a valid VCPR relationship.

Here are the steps to follow for injecting a vaccine or prescribed medication intramuscularly:

  • Have an experienced handler hold your horse, especially if you don’t know how your horse will react. Use a properly fitted halter and lead rope. Have the handler stand on the same side as the person doing the injection. When injecting into the hindquarters, be sure to stand to the side and reach around back – don’t stand behind the horse in case the animal kicks out.
  • Make sure your target area is clear of obvious dirt and debris. Although it’s common to give needles without disinfecting the area first, it’s always a good idea to practice reasonable cleanliness. If needed, scrub the area with soap and water or wipe it with an alcohol gauze.
  • Find the horse’s anatomical landmarks by palpating with your hand and use them to determine your target area. Using your non-dominant hand (left hand if you’re right-handed), pinch the skin just in front of the area you want to inject. This distracts the horse while you insert the needle and makes it less of a surprise.
  • Remove the needle from the syringe – if the horse reacts, you’ll have more control over the needle by itself than if the syringe is attached. Insert the entire needle in a fast and smooth motion, aiming for the centre of your target area.
  • Attach the syringe to the needle and aspirate (gently pull back on the plunger) to check for blood. If you see blood in the syringe or in the needle hub before attaching, you’ve hit a blood vessel. If this is the case, pull the needle out half-way and re-insert into a slightly different area of the muscle mass. Re-aspirate in the new area.
  • If there is no sign of blood, go ahead and depress the plunger to dispense the medication. No more than 15 millilitres (ml) of liquid per injection site is recommended.

Citrus Sacrifice
If you’re needle shy, it can help to try a few practice jabs on a grapefruit or an orange first. Piercing the needle through the peel feels similar to equine skin. It can help you learn how much pressure is needed to inject the needle and lets you practice attaching and handling the syringe.

Note that needles come in varying widths and lengths; most needles used for injections in horses are between 5/8” (1.6cm) to 1.5” (3.8cm) in length. Syringes also come in different sizes; the size should match the volume of medication given so you are accurate when drawing up the medication. Ask your vet which supplies suit the vaccine or medication you’re planning to inject.