By Russ Daly
Special to the Farm Forum
Many cattle producers are starting to plan for pre-weaning calf vaccinations, while some in the drier parts of the region have already begun this task. These vaccines’ ability to prevent disease depends upon many different factors – some we can control and some we can’t. We depend upon the calf’s system to respond to the vaccine appropriately. But the calf depends on us to deliver a fully potent dose of vaccine. When we vaccinate a calf are we robustly stimulating his immune system, or are we injecting a worthless syringeful of liquid under his skin? The answer lies in how we handle the vaccines. Now is a good time to get reacquainted with some of these vaccine handling do’s and don’ts.
First, some things to do. Do understand the differences in handling modified-live (MLV) versus killed vaccines. In order for an MLV vaccine to work, the germs inside need to be viable and able to multiply inside the animal. If they die, there’s not enough of them to stimulate immunity. While we can get away with more handling errors with killed vaccines, they need to be protected from the big three threats to vaccine viability, too: age, heat, and light.
Do mark the syringes used for MLV vaccines. If you forget, and draw up MLV vaccine into a syringe containing leftover killed vaccine, the MLV vaccine will probably be inactivated. A piece of electric tape is one way to easily designate the MLV syringes.
Do put a new needle on the syringe before drawing up vaccine from the bottle. Even clean-looking needles are contaminated when they’ve been used on an animal. Sticking a used needle in the vaccine bottle will contaminate the whole bottle.
Do check your refrigerator temperature – the one you store vaccines in. You may find that your “old reliable” fridge doesn’t keep vaccine in the right temperature range (35-45 F). Over longer storage times, temps too high or low can reduce vaccine potency.
Do continue to protect vaccine during the job. Chute-side, take steps to keep the vaccine at refrigerator temperatures and out of sunlight. Coolers with ice packs are good for this purpose. Think about syringes too – a small cooler tipped on its side on the working table can help keep the vaccine in the syringe cool and out of UV light.
And now for some don’ts. Don’t rely on vaccines to work after their expiration date. While I’ve never considered a vaccine to magically disintegrate at midnight on its actual expiration date, we know that the vaccine company has assured us the vaccine will remain potent only up until that date. After that, no one really knows.
Don’t let vaccines get above refrigerator temperature – ever. This means from the time you take it out of the display cooler at the vet clinic, to the ride home in the pickup, to the refrigerator, to the… you get the picture.
Don’t get overly germ-a-phobic about your syringes. Clean syringes are good – don’t get me wrong. But using disinfectants inside a syringe can inactivate MLV vaccines, even if just a trace of the disinfectant remains. There are methods for cleaning syringes with hot distilled water that work well.
Don’t buy large bottles of MLV vaccine unless you can work through the cattle in a timely fashion. The underlying issue is that once mixed, a MLV vaccine is only viable for a matter of hours. A good rule of thumb is to not mix up more MLV vaccine than you can use in an hour. If it takes you all afternoon to work your 50 calves, buy five 10-dose bottles rather than one 50-dose bottle.
Don’t expect to return vaccines after you’ve purchased them. The issue here is that the veterinarian or supplier can’t guarantee that the “cold chain” has been maintained while it’s out of their hands. After all, you wouldn’t want to buy vaccine that was just returned by someone who left it in a hot pickup the prior afternoon.
The need for proper vaccine handling is an economic issue as well as an animal well-being issue. Keep some of these tips in mind as fall vaccination season commences. For details and more information, your local veterinarian is the best resource you could ask for.
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.