Pet vaccine reactions mostly mild, rare

Ask the Vet

Q: My neighbor was telling me about her dog, “Milo,” and the reactions “Milo” has to his annual vaccinations. My dog has never had a problem with any of her shots. I’ve never even heard of pets having reactions to their shots. Can you tell me more? G.O., Knoxville

A: Yes, dogs and cats may both have vaccine reactions. Certainly, most of the time, nothing happens. Local pain, soreness and mild lethargy can occur, but is generally self limiting and lasts no longer than one or two days.

Rarely seen, but hives, rashes and welts can also occur. Swelling will typically start around the face and muzzle, and sometimes can happen even just a few minutes after the vaccine is given. Gastrointestinal distress has also been documented, but is also uncommon.

Complete anaphylaxis is thankfully rare.

Pets that have had previous vaccine reactions are often pre-medicated with antihistamines and corticosteroids to prevent the allergic reaction. With pets that have had severe reactions, hospital observation for 6 to 8 hours after the vaccine is ideal. Some pets have had such severe reactions that a veterinarian may determine not to vaccinate anymore.

Dachshunds, chihuahuas and pugs are among the breeds that have a higher incidence of vaccine reactions. In general, smaller dogs and younger dogs tend to react more than older or large breed dogs.

Please remember, most pets will experience minimal to no side effects, and it is important to keep your pet protected with immunizations.

If you have concerns that your pet may have had a previous reaction or have questions about vaccines in general, talk with your veterinarian. He/she can guide you in making health care decisions for your pet.

If you have questions about your pet, you may e-mail Dr, Myers at