Vaccine Reactions in Pets

Vaccine Reactions in Pets

After receiving a vaccine, it is normal for pets to experience certain side effects which usually start within hours after the vaccination. It’s important to note that if the below side effects last for more than a day or two, or if your pet is in visible discomfort, then you need to contact your veterinarian immediately.

These side effects include:

• Mild fever
• Decreased appetite and activity
• Discomfort and local swelling at the vaccination site
• For intranasal vaccines, pets may experience sneezing, mild coughing, runny nose or other respiratory signs, which may occur 2–5 days after the vaccine

More severe but less common side effects (including allergic reactions) can also occur as soon as minutes or hours after a vaccination. These reactions are medical emergencies and can be life-threatening. If you notice any of these signs, seek veterinary care immediately:

• Persistent diarrhea or vomiting
• Itchy, bumpy skin or hives
• Swelling around the face, neck, eyes and muzzle
• Difficulty breathing or severe coughing
• Collapse

You may also notice a small, firm swelling under the skin where the vaccine was administered. This should begin to disappear within a couple weeks—if it persists more than three weeks, or if it gets bigger, please contact your veterinarian.


At PAVG, we are always committed to making sure your pet stays happy and healthy. If you suspect your pet may be experiencing a reaction to a vaccine, or if you notice any of the above symptoms, please contact us at our following locations:

Chillicothe: 309-273-1909
Dunlap: 309-439-9522
Dunlap II: 309-413-0527