What do vaccines actually do?
A vaccine trains an animal's immune system to recognize a disease before it meets the real thing. It is not a treatment for an animal that is already sick, and it is not a guarantee. Some vaccines need a first round and a follow-up before they protect, and protection may wear off, so timing matters.
Vaccines are one part of herd health, alongside clean housing, good nutrition, low stress and quarantine of new animals. A vaccine cannot make up for a crowded, muddy or poorly fed setup.
Keep in mind that immunity takes time to build. An animal vaccinated today may not be fully protected for days or weeks, and young animals that nurse may carry protection from their mothers that changes how and when they should be vaccinated. Your vet can explain how this applies to your animals.
Which vaccines does my herd need?
There is no single list. The right plan depends on your species, age and sex, whether you breed, whether animals leave the farm for shows or sales, whether you bring animals in, and which diseases are common in your region.
Ask your veterinarian to design a plan for your herd and write it down. Your county extension office can also tell you what problems are common locally. Avoid copying a neighbor's program or buying products because a feed store shelf has them.
How should vaccines be stored and handled?
Most vaccines must be kept cold and protected from light and from freezing, and a vaccine that was left warm may no longer work, even though it looks fine. Read the label for storage instructions on every product and follow it.
Take only what you need to the barn and keep it cool and shaded in a insulated carrier during use. Do not mix products unless the label says you can, use the contents within the time stated once opened, and throw away what is left rather than saving it.
- Check the expiration date before buying and before using
- Keep a thermometer in the refrigerator you use for vaccines
- Never use a vaccine that has frozen or sat in the sun
- Dispose of opened vials and used needles safely, in a sharps container
- Use clean needles and change them often, as your vet directs
Who should give the shots?
Rules about who may buy and give certain vaccines differ by state and product. Many are available to owners, and some require a veterinarian. Ask your vet to show you the correct technique, injection site and restraint for your species before you do it yourself.
Poor technique can cause abscesses, lameness or damaged meat, and a needle stick can hurt you. Have help, keep animals calmly restrained and never rush.
If you buy vaccines from a supplier rather than your vet, still share the product names with your vet so the plan stays coordinated and nothing is doubled up or missed.
What can go wrong after vaccinating?
Mild soreness or a short period of reduced appetite can occur, and your vet will tell you what to expect. Severe reactions such as collapse, trouble breathing, swelling of the face or a very sick animal are emergencies, so call the vet at once.
Keep your phone nearby and vaccinate on a day when the vet's office is open, not before a weekend or holiday. Pregnant animals may need special consideration, so ask before vaccinating any that are bred.
What records should I keep?
For each animal record the product name, the date given, the lot number and expiration printed on the bottle, who gave it and where. Keep the label or a photo of it.
These records help you remember boosters, help your vet adjust the plan, and may be required when animals are sold, shown or moved across state lines. Rules for movement and health papers are set by the state veterinarian, so ask that office when planning to move animals.
How do I decide when to vaccinate in the production cycle?
Timing depends on the animal's age, the vaccine and the stage of production, such as before breeding, during pregnancy or before weaning. Your vet can lay this out on a simple calendar for your herd, and it is worth having it on paper rather than in memory.
Plan vaccination days like any other farm project. Have animals penned, supplies ready and help on hand. Avoid vaccinating animals that are already sick or severely stressed unless your vet says otherwise, and avoid scheduling during extreme weather. After each session, update your records and set reminders for boosters so that the calendar works for you.
- Write the schedule on a calendar you actually see
- Keep vaccination days calm and organized
- Set booster reminders at the time of each shot
- Review the plan with your vet every year
Key takeaways
- Vaccines prevent disease but do not treat sick animals.
- Your vet should design the plan for your species and region.
- Keep vaccines cold, protected from light and within date, per the label.
- Learn technique from a professional and watch for reactions.
- Keep dated records with product and lot information.
Sources and further reading
Last reviewed: November 12, 2026. Written by the Homestead & Small Farm Editorial Team. See our editorial policy.