Adverse Vaccination Reactions
We feel it is important for all our clients to understand the various clinical signs that may be associated with adverse
vaccination reactions in pets. Overall, adverse vaccination reactions are very rare and the benefits of vaccinating pets
against disease outweigh the risks of adverse vaccination reactions.
The first type of reaction that can occur is an immediate reaction, which is usually the result of an allergy to one or more
components of the vaccine. This reaction typically presents within an hour of administering the vaccination. Symptoms
of this type of reaction include vomiting, diarrhea, difficulty breathing, and facial itchiness and/or swelling. If your pet is
exhibiting any of these symptoms, it is very important they be seen immediately by a your regular veterinarian (or an
emergency veterinarian if it is after hours). In very rare cases, this reaction can be more serious and result in shock and/or
sudden death.
The second type of reaction is more delayed and tends to occur within 24 to 48 hours of administering vaccinations. In
this case, the pet may suffer joint or muscle soreness at the site of administration of the vaccination. The pet may also
exhibit signs of lethargy, a decrease in appetite, and a mild fever may be noted. These symptoms usually resolve on their
own, we advise contacting your regular veterinarian (or an emergency veterinarian if it is after hours) for their
recommendations.
The third type of reaction that can occur is a localized swelling or lump at the site of administration of the vaccination.
This usually occurs 2 to 4 weeks after the administration of the vaccine and is the result of immune stimulation and
inflammation at the injection site. If the lump does not resolve naturally, it should be evaluated by a veterinarian.