One of the most important aspects of quality in our industry is performing injections properly. Let's cover some basics.
Adequate restraint is a basic requirement. Every effort should be made to have the animal still when administering an injection.
Needle movement during intramuscular (IM) injections increases muscle damage, and could cause a significant portion of the injection to be deposited subcutaneously (SC). Movement during SC injections may lead to a significant portion of the injection ending up IM.
In either case, the result is a product in a different site than intended. This may affect efficacy and, in some cases, contribute to an altered withdrawal time.
The SC “tented technique,” where the skin is pinched and raised with one hand while injecting parallel to the hide with the other hand, should only be used when the animal is restrained in a squeeze chute or otherwise completely immobile.
Proper injection sites must be periodically reviewed. The injection site audit work available to our industry illustrates the importance of staying away from the top butt for all injections and confining IM injections to the neck.
Even within the neck region, there are specific areas to target for IM injections. The best way to learn the boundaries of the injection site triangle in the neck is to ask for an anatomy lesson from your veterinarian (especially during a necropsy) or attend an injection site demonstration.
If you're giving IM neck injections in front of the head gate, you're likely giving injections too far forward in the neck. Consider SC-labeled products whenever possible.
Separation between injection sites is as important as site selection. Moving the needle only an inch or two between sites essentially creates one big site. Moving a hands-breadth away for the next site is a good rule to follow.
On small calves, this may mean only two to three injections/side of the neck. Consult the label and your veterinarian before moving behind the shoulder for SC injections over the ribs. If you find yourself routinely running out of injection sites, it's time for an in-depth evaluation of your preventive and therapeutic programs.
Read and follow volume-per-site instructions. This isn't an issue for most vaccines due to smaller injection volumes, but it's extremely important for antibiotics. It's a rare case where more than 10-15 ml./site is indicated. (An ml. is equivalent to a cubic centimeter, abbreviated as cc.)
An example of setting yourself up for a residue violation would be administering 50 ml. of procaine penicillin G (or worse, a “long acting” penicillin) in one SC site to a big steer with footrot. This large volume will be absorbed more slowly, which will definitely increase the necessary slaughter withdrawal time and possibly prevent adequate concentrations being reached at the site of infection. Any use of a drug differing from label directions requires a valid veterinary-client-patient relationship with an extended withdrawal time.
Needle selection and care are essential to quality assurance. A 16-ga. needle is the maximum size for IM injections. Try keeping antibiotics warm in the winter rather than resort to a 14-ga. needle. Or consider cold-weather injection characteristics through a 16-ga. needle during drug selection consultations with your veterinarian.
An 18-ga. needle may be used for administration of some products, but proper restraint becomes more important to avoid bending and possible breakage of these small needles.
Discard bent needles. Never straighten and reuse them due to potential breakage.
Needle length for SC injections should not exceed ¾ in., and ⅝ in. may be your best choice. Many IM injections can be accomplished with a 1-in. needle. If you feel resistance as the needle penetrates the hide, check for barbs. It's probably time for a new needle.
Protecting product integrity (sterility and efficacy) includes always drawing the product from the original container and paying attention to sanitation of syringes and injection systems. Hopefully, our industry has moved beyond the inappropriate practice of mixing multiple containers of products together in large bags at the chute.
A new sterile needle should be used every time you draw product from a multiuse container that will not be used immediately. The rubber stoppers in these bottles also tend to dull needles very quickly. And, remember that even traces of soap or disinfectants left in syringes can inactivate modified-live viral vaccines.
Remember that your injection techniques have a big impact on meat quality, personnel safety and product efficacy. Review your practices with your herd health veterinarian.
Mike Apley, DVM, PhD, is an assistant professor of beef production medicine at Iowa State University in Ames. W. Mark Hilton, DVM, is a clinical assistant professor of beef production medicine at Purdue University in West Lafayette, IN.