Pigs as young as 6 weeks old can receive vaccines to protect them from common diseases like swine fever, aujeszky's disease, and foot-and-mouth disease. The majority of vaccines are administered by subcutaneous injection, which means that it's underneath the skin but over the muscle. Intramuscular is the second best option. Veterinarians offer these vaccines, but you can apply them yourself in a few steps.
Pull back on the syringe so that you draw in some air equivalent to the dosage needed for the vaccine. For example, if your swine fever vaccine calls for 3cc's of medicine, draw in 3cc's of air.
Stick the syringe needle through the medicine vial and push down so that the air is infused. Pull back on the plunger to suck the medicine into the syringe. Lightly pluck the side of the syringe to get rid of any air pockets that may have formed.
Walk up to the pig and back it down, not letting it move past you. Once space is cut off and you have the pig backed into a corner, most will sit back on their back legs.
Locate the most feasible area of injection. The best point of injection for a subcutaneous injection is behind the pig's shoulder or the skin inside of the thigh. The two best places to inject a pig for an intramusclar injection are on the neck behind the ear, and on the buttocks.
Press the needle into the injection point in a swift motion at a 90-degree angle, quickly pushing down on the syringe lever so that the medicine is injected. Pull the syringe straight out once it is empty of vaccine.
If your pig is especially squirmish or hyperactive, it may also help to set down a meal or a treat to distract it while you administer the shot.
Most pigs don't enjoy sitting still for shots, so it'll be a pain trying to prepare the syringe after catching the pig as opposed to beforehand.