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Vaccine Reactions in Dogs: Everything You Should Know

Your dog's vaccinations shield them from various serious illnesses, yet owners frequently worry about potential adverse reactions. Our vets in Los Angeles discuss the most prevalent reactions dogs may experience after vaccinations and provide guidance on handling any reactions your dog might have to their shots.

Why are vaccines recommended for dogs?

Annual vaccinations are critical in preventing your dog from contracting serious contagious diseases that can endanger their long-term health. Typically, the benefits of vaccinating your dog outweigh the risk of your dog developing a vaccine reaction. However, some dogs react to getting their shots.

Common Side Effects of Vaccinations in Dogs

Witnessing your pet experience an adverse reaction to vaccines can be distressing. However, responsible pet owners must remember that most reactions are mild, brief, and generally less hazardous than the illnesses the vaccines guard against. Even instances like your puppy briefly crying or yelping after vaccinations are short-lived.

Knowing the typical vaccine reactions in dogs and taking appropriate action if your dog reacts to their shots can make the vaccination process less stressful for both you and your pet.


Lethargy, mild discomfort, and a slight fever are typical responses dogs may have to vaccines. If your dog seems less energetic than usual or experiences difficulty walking after shots, it's a normal reaction, and these symptoms should be mild, lasting only a day or two. If your dog's reaction persists beyond a couple of days, contact your vet promptly.

Lumps & Bumps

Dog vaccinations can cause lumps and bumps as common side effects. After the immunization, monitor the injection site for a small, firm bump. It's a normal reaction, but watching for any signs of growth, inflammation, oozing, or increased pain is crucial. The lump should gradually disappear within about a week. If signs of infection persist or if the bump doesn't go away after a week, contact your veterinarian.

Whenever the skin is punctured, there's a risk of infection. Keep a close eye on the site where your dog received the injection. Look out for signs of infection, such as heightened redness, swelling, pain, or discharge. Untreated infections can lead to more serious conditions. Contact your vet promptly if you observe inflammation and soreness at the injection site.

Sneezing & Cold-Like Symptoms

Most dog vaccines are injected, but the Bordetella bronchiseptica and parainfluenza virus vaccines are given as drops or sprays into the dog's nose. If your dog experiences intranasal vaccine reactions, expect symptoms like a runny nose, coughing, and sneezing—similar to a cold. These symptoms should clear up within a day or two. If they persist or worsen, contact your veterinarian promptly. 

Serious Reactions to Vaccinations

Vaccines usually cause brief and mild reactions, but in rare cases, they can trigger severe reactions that require immediate medical attention. Anaphylaxis, a severe allergic reaction, presents with symptoms such as facial swelling, vomiting, hives, itchiness, diarrhea, and difficulty breathing. In dogs, anaphylaxis typically manifests shortly after vaccination, though it's crucial to be aware that it can occur up to 48 hours post-vaccination.

If your dog shows symptoms of anaphylaxis following their shots, call your vet immediately or contact your emergency veterinary clinic.

Preventing Reactions to Vaccines

Vaccines are essential in protecting your dog against a number of potentially fatal and contagious diseases. The risk of your dog having a serious reaction to a vaccine is very low. 

Be sure to let your vet know if your dog reacts to vaccines. Your vet may recommend that you skip a particular vaccination in the future.

When multiple vaccines are given together, the risk of adverse reactions to vaccinations may be increased, especially in smaller dogs. Your vet may advise spreading out your dog's vaccinations over several days rather than all at once to reduce your dog's risk of allergic reactions.

Contact our Los Angeles vets at Ambassador Dog & Cat Hospital today to find out more about vaccines and other preventive healthcare. 

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