August is National Vaccination Awareness Month, a time dedicated to promoting the importance of pet immunization. While dog vaccines offer immense benefits, it’s essential to acknowledge that they can sometimes lead to side effects. Understanding what vaccine reactions look like in dogs and how to respond can help ease your concerns about vaccinating your pet. In this post, we aim to address common questions and concerns related to dog vaccinations. 

Three Common Vaccine Reactions in Dogs

The following side effects are relatively common, but typically resolve within a day or two. If they persist or cause severe discomfort for your dog, please don’t hesitate to contact us. Here are the three most frequent vaccine reactions:

1. Lethargy and Soreness

It’s very common for a dog to seem lethargic or sore after their shots. Sometimes, these symptoms are accompanied by a mild fever. These reactions are signs of your dog’s immune system responding to the vaccine. This is the whole point of a vaccine, so this response is completely normal and expected. Most dogs are back to their normal selves within a day or two. However, if your dog has more severe or prolonged soreness or lethargy, or just seems “off,” give us a call—we may be able to prescribe medications that will help your pup feel better.

2. A Bump or Lump

When a vaccine is injected under the skin or into a muscle, you may notice some swelling or a small soft lump or bump at the injection site. This happens because the vaccine irritates your dog’s tissues, leading to a surge of immune cells in the area. A vaccine lump typically lasts a day or two in dogs. The lump may be tender to the touch, which is normal. However, if you notice the lump is big after a few days, starts oozing, or becomes more painful, let us know right away. If swelling persists, your veterinarian may want to perform tests to assess the possibility of a vaccine granuloma.

3. Sneezing and Runny Nose

Some vaccines are administered as drops or a spray squirted into your dog’s nostrils. The vaccines that protect your dog from Bordetella bronchiseptica and parainfluenza virus are the most common intranasal vaccines. 

These vaccines are given through the nose because these diseases are all contracted in the respiratory tract. So it’s not too surprising that adverse vaccine 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 symptoms aren’t anything to be alarmed about.

Less Common Vaccine Reactions in Dogs

Although very rare, some dogs may experience more severe adverse reactions to vaccines. If you think that your dog is having a serious reaction, contact us or your closest emergency vet immediately.

1. Anaphylaxis

Anaphylaxis is a potentially life-threatening allergic reaction. This reaction will occur shortly after receiving the vaccine (usually minutes to hours). Symptoms of anaphylaxis in pets include hives, itchiness, facial swelling, vomiting, diarrhea, and/or difficulty breathing. 

2. Infection 

While rare, any injection can cause an infection or abscess as bacteria can enter the body through the skin and into underlying tissues. Symptoms to look out for include discolored skin (often red), discomfort, discharge, and swelling at the injection site.

How to Prevent Vaccine Reactions in Dogs

It is important to keep in mind that vaccination will not result in a severe adverse reaction for most dogs. However, if your dog has previously had a bad reaction to a vaccine or has underlying health issues, please let us know. It may be best to change or even skip certain vaccines. In these cases, we may perform titer tests, which can determine if previously administered vaccines are still providing protection for your dog, or if boostering is needed. Either way, your dog’s comfort and safety are our number one priorities. 

Vaccine Spacing 

The risk of mild vaccine reactions in dogs (lethargy, soreness, fever, etc.) can increase when multiple vaccines are given at the same time. More frequent vet visits with fewer vaccines per visit may lower the risk of these mild vaccine reactions if this is something you are concerned about. We can help you decide if the added cost, time, and stress of multiple vet visits are worth the lower risk, but ultimately it is up to you. 

Give us a Call 

In the unlikely event that your pet has an adverse reaction to their vaccinations like a lump or persistent tiredness, Anasazi Animal Clinic in Gilbert is here to offer our expert medical advice and care. Call us right away. And if you don’t already have a local vet you love, come in and see us! We’d be honored to care for your pets and give them the quality treatment and preventative care they deserve. 


Image by Cedric Clooth from Pixabay