Vaccine Reactions in Dogs: Side Effects and What You Should Know

Jennifer Coates, DVM
Vet Reviewed
By Jennifer Coates, DVM on Dec. 28, 2017
Vaccine Reactions in Dogs: Side Effects and What You Should Know

Reviewed and updated for accuracy on August 11, 2020, by Matthew Everett Miller, DVM

For the vast majority of dogs, the benefits of appropriate vaccination far outweigh the risks. However, as is often true in medicine, dog vaccine side effects are possible.

Vaccine reactions in dogs can be stressful and scary for you as a pet parent, but they will be less so if you know what to watch for and how to react.

Common Vaccine Reactions in Dogs

Here are three common side effects of dog vaccines and how to treat them, as well as several less-common conditions caused by vaccination.

Feeling “Off”

The most common vaccine reactions in dogs are lethargy and soreness, which may or may not be combined with a mild fever. This occurs because the dog’s immune system reacts both locally and systemically to vaccine administration.

Prompting the immune system to respond is the whole point of vaccination. After receiving a vaccine, if your dog comes in contact with the pathogen in the future, their immune system can respond quickly and effectively, which reduces the chance that serious illness will result.

Thankfully, most pets are back to their normal selves within a day or two of vaccination. If your dog has more severe or prolonged soreness or lethargy, call your veterinarian. They may prescribe medications that will help your pup feel better.

Lumps and Bumps

When a vaccine is injected under the skin or into a muscle, a small, firm bump (or swelling) may develop at the site because of local irritation and immune cells rushing to the area.

The lump may be somewhat tender to the touch but should not grow (after the first few days), ooze, or become more painful as time passes.

Unless any of these more serious dog vaccine side effects are noted, just keep an eye on the area. If swelling persists, your veterinarian may want to perform tests to assess the possibility of a vaccine granuloma.

Ordinary lumps and bumps associated with vaccines resolve on their own over the course of a few weeks. If this does not occur, make an appointment with your veterinarian.

Sneezing and Sniffling

Most vaccines are given by injection, but a few are administered through drops or a spray squirted into your dog’s nose. The most commonly used intranasal vaccines for dogs are those that protect against Bordetella bronchiseptica and parainfluenza virus.

Intranasal vaccines were developed, in part, because these diseases are all respiratory in nature, and dogs can become infected through their noses. So it makes sense to give a nasal vaccine to encourage immunity to develop at the first spot where an infection might develop.

However, it’s not too surprising that adverse reactions associated with the respiratory tract are also possible. Dogs may sneeze, cough, or develop stuffy/runny noses for a few days after intranasal vaccines.

These types of vaccine reactions in dogs should resolve on their own within a day or two. If they don’t, call your veterinarian for advice.

Less Common Vaccine Reactions in Dogs

On rare occasions, pets will have more serious reactions to vaccines. If you suspect that your pet is having a serious adverse reaction to vaccination, contact your veterinarian immediately.


A potentially life-threatening allergic reaction called anaphylaxis is one of the scariest. Soon after vaccination (usually minutes to hours), a dog undergoing anaphylaxis typically develops hives, itchiness, facial swelling, vomiting, diarrhea, and/or difficulty breathing.

Infection or Abscess

Additionally, any type of injection can lead to an infection or abscess where bacteria can gain entry through the skin and into underlying tissues. Signs to watch for include discolored skin (often red), discomfort, discharge, and swelling.

Is There a Risk of Reactions in Dogs With Immune-Mediated Diseases?

For dogs with immune-mediated diseases, there is a theoretical risk that vaccination could induce a relapse of that disease. However, research has not proven a link between vaccination and the development of these diseases.

In fact, for dogs with the most common immune-mediated disease, immune‐mediated hemolytic anemia, the American College of Veterinary Internal Medicine says, “current vaccination strategies generally are safe,” but adds that individual patients should be assessed by a veterinarian when weighing the risks and benefits of vaccination.

Preventing Vaccine Reactions in Dogs

It is important to remember that for the vast majority of dogs, vaccination will not result in a significant adverse reaction but will protect against potentially serious diseases.

Talk to Your Vet About Titer Tests or Skipping Certain Vaccines

That said, if your dog has previously had a bad reaction to a vaccine or has underlying health problems, talk to your veterinarian. It may be in your dog’s best interest to change or even skip certain vaccines that would otherwise be given routinely.

In these cases, your veterinarian may suggest titer tests, which can determine if previously administered vaccines are still providing protection for your dog, or if boostering is needed.

Schedule More Vet Visits With Fewer Vaccines

Research has shown that the risk of mild vaccine reactions in dogs (lethargy, soreness, fever, etc.) does increase when multiple vaccines are given at the same time, particularly in dogs that are young adults, small breeds, or neutered.

One study also found that these mild vaccine reactions are more common when the leptospirosis vaccine has been given. Note that severe, life-threatening vaccine reactions in dogs do not occur more commonly with multiple vaccines nor with the lepto vaccine.

More vet visits with fewer vaccines per visit may reduce the risk of the mild vaccine reactions. Only you can decide if the added cost, time, and stress of multiple vet visits is worth the reduction of risk.

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Jennifer Coates, DVM
Vet Reviewed


Jennifer Coates, DVM


Dr. Jennifer Coates is an accomplished veterinarian, writer, editor, and consultant with years of experience in the fields of veterinary...

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