What to Expect After Your Pet’s Vaccination

Animal Vaccination Information

Brought to you by your veterinarian and the American Veterinary Medical Association

It’s common for pets to experience mild side effects after receiving a vaccine, usually starting within hours of the vaccination.


The following side effects aren’t unusual. However, if they last for more than a day or two, or cause your pet significant discomfort, it’s important for you to contact your veterinarian.

  • Discomfort and local swelling at the vaccination site

  • Mild fever

  • Decreased appetite and activity

  • Sneezing, mild coughing, “snotty nose” or other respiratory signs occurring 2-5 days after your pet receives an intranasal vaccine


More serious, but less common side effects, such as allergic reactions, may occur within minutes to hours after vaccination. These reactions can be life-threatening and are medical emergencies.

  • Persistent vomiting and diarrhea

  • Itchy skin that may seem bumpy (“hives”)

  • Swelling of the muzzle and around the face, neck, or eyes

  • Severe coughing or difficulty breathing

  • Collapse

A small, firm swelling under the skin may develop at the site of a recent vaccination. It should start to disappear within a couple weeks. If it persists more than three weeks, or seems to be getting larger, you should contact your veterinarian.

Always inform your veterinarian if your pet has had prior reactions to any vaccine or medication. If in doubt, wait for 30-60 minutes following vaccination before taking your pet home.

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