By Russ Daly
Special to the Farm Forum
In a previous column, I discussed some of the things to keep in mind when vaccinating animals this fall. Avoiding contamination and maintaining vaccine viability are two major principles that, when followed, give the vaccine the best chance to do what it’s supposed to do – protect the animal from harmful disease.
It turns out that how we treat our animal vaccine syringes can play a major role in both of those issues. When you think about it, those tools are awfully important. If you’re like most farms, every dose of vaccine that goes into one of your animals travels through one or two of those syringes. A problem in one syringe can create trouble for the whole herd.
Bacterial contamination of a syringe is one of those problems. A syringe containing loads of “junk” bacteria in its barrel will inoculate those germs right into the animal. This shows up in the animal as abscesses at the injection site. Several days following vaccination, the injection site will swell up with pus, creating a painful situation for the calf, lamb, or pig that received the shot. What’s more, the vaccine likely isn’t going to work when such infection is present.
Now, post-vaccination injection site swellings are not uncommon in farm animals. In fact, some swelling indicates that the animal’s immune system cells are processing the vaccine. But this type of swelling isn’t usually filled with fluid, nor is it usually bigger than a hen’s egg. Treatment isn’t necessary for “normal” injection site swellings.
On the other hand, infected, abscessed injection sites usually require treatment. When they have reached the proper stage, they can be surgically lanced so that fluid can drain from the site. Over the years, I have drained some astoundingly large injection site abscesses containing quarts – yes, quarts – of stinky fluid.
A single injection site abscess within a group of your animals might simply be bad luck, but when it affects a high percentage, investigation is in order. And the place to start is with your syringes. Over time, residue left from vaccines will breed bacteria and molds in the syringe barrel if they’re not cleaned out right after use. Other situations, such as burred or dirty needles, vaccine bottle contamination, and vaccinating wet animals, also cause injection site abscesses, but syringe contamination should always be addressed when these problems pop up.
So in order to prevent injection site abscesses, we just need to clean and disinfect the heck out of our syringes, right? Not so fast! Using soap or disinfectants inside the syringe barrel is a sure-fire way to ruin some vaccines. (On the outside of the syringe you can use whatever you like, though). Even after repeated rinsing, a trace of soap or disinfectant remaining in the barrel can inactivate a modified-live vaccine. This is the other problem our vaccine syringes can bring to the table – an invisible problem, at that. You’ll never know whether those sick animals were because of a disease that overwhelmed their protection, or whether the vaccine simply wasn’t any good when it was injected into the animal.
How can we get the inside of syringes clean without using soap or disinfectants? The answer is through repeated rinsing with very hot water. Hot water, brought to the boiling point in a microwave, then drawn up into and squirted out repeatedly (3-5 times) from the syringe will remove any remaining vaccine in the barrel, and kill any germs that might have gotten in. If doing this right before a job, you’ll need to allow time for the syringe to cool down before reloading it – heat will kill modified live vaccines too. If the syringes won’t be used for a while, store them so they can’t become re-contaminated. Keeping them in a zip-lock bag in a freezer is one idea I’ve heard.
A great source for information about pistol-grip syringe care is your local veterinarian. While you might pull your syringes out once or twice a year, your vet uses them every day.
If you have a good vaccination plan for your animals, you’re already taking great steps to keep your animals healthy and productive. Make sure the tools you use to deliver those vaccines aren’t short-circuiting those efforts.
Russ Daly, DVM, is the Extension veterinarian at South Dakota State University. He can be reached via e-mail at [email protected] or at 605-688-5171.