Skip to Main Content
Ask About Financing

Vaccine Reactions in Dogs: Everything You Should Know

Vaccine Reactions in Dogs: Everything You Should Know

Vaccinations protect your dog against a number of serious illnesses, but owners are often concerned about the risk of adverse reactions to vaccines.  Today, our Denver vets explain the most common reactions dogs have to vaccinations, and what to do if your dog has a reaction to getting their shots.

Why are vaccines recommended for dogs?

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

Common Side Effects to Vaccinations in Dogs

Seeing your pet have an adverse reaction to vaccines can be upsetting. Nonetheless, it's important for loving pet owners to keep in mind that most reactions are mild, short-lived, and typically far less dangerous than the illnesses the vaccines protect against. Even stuff like your puppy crying or yelping from picking them up after vaccinations is short-lived.

Understanding the most common vaccine reactions in dogs and what to do if your dog has a reaction to getting their shots can make vaccination time less stressful for you and your pet.


Being lethargic, mild discomfort, and a slight fever are the most common reactions to vaccines in dogs. This is often characterized by your dog just not acting like its usual self; perhaps being a little more lazy than normal. This might include your dog having trouble walking after shots. This is a normal reaction to vaccinations in dogs, and the symptoms should be mild and only last a day or two. If your dog's reaction continues for more than a couple of days, contact your vet.

Lumps & Bumps

Lumps and bumps are common side effects of dog vaccinations. Following the vaccinations, a small, firm bump may form where the needle was injected into the skin. This is a normal reaction, but it is important to keep an eye on the bump to ensure that it does not continue to grow or show signs of infection, such as becoming inflamed, oozing, or becoming more painful. Over the course of about a week, the lump should gradually disappear. Contact your veterinarian if the lump shows signs of infection or does not disappear after about a week.

There is a chance of infection any time that skin is punctured. Keep an eye on the site where your dog's injection was given. Watch for signs of infection such as increased redness, swelling, pain, or discharge. Infections can lead to more serious conditions if left untreated. If you notice that the spot where your dog had their injection is becoming inflamed and sore, contact your vet.

Sneezing & Cold-Like Symptoms

The majority of dog vaccines are administered via injection; however, the Bordetella bronchiseptica and parainfluenza virus vaccines are administered via drops or sprays into the dog's nose. Intranasal vaccine reactions resemble a cold, with symptoms such as a runny nose, coughing, and sneezing. Your dog should recover from these symptoms in a day or two. Call your veterinarian if your dog does not recover within a few days or has more severe symptoms.

Serious Reactions to Vaccinations

Vaccine-related reactions are typically brief and mild. However, in a few rare cases, more severe reactions necessitate immediate medical attention. Anaphylaxis is a severe allergic reaction characterized by facial swelling, vomiting, hives, itchiness, diarrhea, and difficulty breathing. Anaphylaxis in dogs typically occurs shortly after vaccination, but it is important to note that it can occur up to 48 hours after 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 has a reaction 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 reaction.

Contact our Denver vets at Downtown Animal Care Center today, to find out more about vaccines and other preventive healthcare. 

New Patients Welcome

Downtown Animal Care Center is accepting new patients! Our experienced vets are passionate about the health of Denver companion animals. Get in touch today to book your pet's first appointment.

Contact Us

Book Online (303) 595-3561