Gerald Hauer, DVM
Bison Production Specialist
Alberta Agriculture, Food and Rural Development
Bison Centre of Excellence, Leduc, Alberta.
Phone: (780) 986-4100
Reprinted from The Tracker, February 1999
Correct administration of medications is important to get the maximum benefit of the product and to minimize the tissue trauma created by needles. This article discusses techniques used when administering medications using the subcutaneous and intramuscular routes in bison and elk.
Vaccines and other medications are used regularly in the care of elk and bison. Last month I discussed the theory of vaccines and why it is important to use them correctly. In this article I will discuss proper injection techniques to ensure that the products that we are giving are working as effectively as possible.
There are several routes available for the administration of medications in domestic livestock. They include intramuscular (IM or in the muscle), subcutaneous (SQ, SC or under the skin), intravenous (IV or in the vein), and topical (pour-on). Intravenous injections are tricky and more risky so they are best left for your veterinarian. Very few drugs used in elk and bison require intravenously injection so we will focus on IM and SQ injections in this article.
The choice of which route (IM or SQ) to use is usually based on the directions on the bottle of medication. Although elk, bison, and deer usually won't be on the label, an acceptable route in other species can be used as a guideline. For example, penicillin is licensed for IM use in cattle, horses and pigs. Therefore, IM would be the best route in elk, bison, and deer as well. Some products such as oxytetracyclines and clostridial vaccines are licensed for IM or SQ administration, leaving you a choice of two routes. If there is any doubt about which route to use, consult your veterinarian for advice. It is better to be safe than sorry!
I will discuss subcutaneous injections first. The trend is to give as many medications as possible by this route as it causes fewer blemishes in the meat cuts at slaughter. For SQ injections a short and sturdy needle works the best. Usually ½ inch,18 gauge or ¾ inch, 16 gauge needle works quite well. The short needle helps keep you from inadvertently injecting into the muscle layer and tends to be a little stronger. However, if you are injecting a big, old, bison bull keep in mind that a half inch needle may not get all the way through the skin on the neck and a ¾ or 1 inch needle may be more appropriate. Subcutaneous injections are generally given on the neck just in front of the shoulder blade or on the upper rib cage just behind the shoulder blade (see diagram 1). There is abundant loose skin in these areas and there is little chance of hitting important internal structures when injecting in these spots. The easiest way to give a SQ injection is to pinch a bit of skin between your fingers to form a fold. Insert the needle into the skin at the bottom of the fold where the loose skin meets the body. Draw back on the plunger of the syringe to see if you are in a blood vessel and if you don't get any blood back into the syringe proceed with the injection. If you are using a multidose syringe it is difficult to draw back on the plunger so the needle is inserted and the injection is given without checking to see if you hit a blood vessel.
Diagram 1- Subcutaneous Injections
Intramuscular injections are used when the subcutaneous route is not an option. For IM injections, the needle must be long enough to penetrate the muscle and a small enough gauge so that the medication doesn't leak back onto the skin or into the subcutaneous tissue. A 1 inch, 18 or 20 gauge needle is the smallest that you would want to use. These work quite well on small animals such as calves or fawns where there isn't a lot of meat covering their bones. In larger and mature animals a 1½ inch by 16 or 18 gauge would be. When selecting the gauge of needle, keep in mind that some drugs are very thick and require the larger gauge just to get through the needle. For example, it is difficult to inject some of the antibiotics through an 18 or 20 gauge needle and you will find that a 16 gauge needle is necessary.
There are a few sites that you can use for giving IM injections. They include the upper neck, the upper rump, and the lower rump. Each site has advantages and disadvantages. In beef cattle there is a big push to use the neck muscles whenever possible because any damage that is done by the injections will be in the lower quality meat cuts instead of the steaks and roasts found in the rump. This is something that you should keep in mind in the bison. In large animals such as bulls and cows there is a lot of muscle in the neck that is easily used for injections. The proper area for injecting in the neck is just in front of the shoulder blade in the upper 1/3 of the neck. Care must be used when using the neck muscles in calves and fawns because there is very little muscle in this area and it is easy to hit the underlying bone. Although this is often the best site to use in young animals, repeated injections can make their neck quite sore and they may refuse to hold up their head to nurse. Sites should be rotated when giving injections over several days so that the muscles in one area don't become too painful.
Another place to give an IM injection is in the upper rump . The advantage of this location is that it tends to be quite accessible in a chute and is generally quite clean. The bad part about this site is that there is some risk in hitting a major nerve to the back leg if the needle is inserted too far back (see diagram 2). To avoid this nerve, insert the needle in the meaty area just behind the hook or hip bone. In a large bull this area is about the size of your hand and in a calf it is only as big as a large coin. The last place that it is possible to give an IM injection is the lower rump, below the tailhead and on either side of the back leg. The problems with this site is that it is often hard to access, animals tend to kick more when poked here, and in smaller animals the nerve can easily be damaged. For these reasons I rarely use this site.
Diagram 2 - Intramuscular Injections
When giving the IM injections tap the muscle a few times to numb the skin and then in the same rhythm insert the needle (tap-tap-tap-poke). The animal usually objects less to the poke when done this way but don't overdo it with the tapping. Insert the needle all the way into the muscle, attach your syringe, and remember to always draw back on the syringe plunger to check for blood before injecting. Inject only 10 mL of medication in any one site so that the drug is readily absorbed and there are fewer muscle blemishes left behind . Also, choose a clean area to inject because we don't want to cause an infection by passing the needle through heavily contaminated skin.
This has been a brief description of injection techniques. If you have any questions or are still not comfortable with giving an IM or SQ injection to your animals, you should call your local veterinarian for some more advice.