Anaphylaxis is the body’s inappropriate, severe response to benign stimuli and can occur following vaccination. Signs of a vaccine reaction include lethargy, swelling, fever, collapse and in severe cases, death. If your animal had a previous anaphylactic reaction to a vaccine, you and your veterinarian should discuss whether the benefits of vaccination outweigh the risk of reaction. Less severe reactions to any injection can occur in the form of swelling at the injection site. If bacteria ar…