Vaccines are biological products and as such can result in adverse reactions in some patients, although these are uncommon. Since the original development of vaccines more than 50 years ago, a continuing effort has been made to make vaccines safer and more efficacious. Today, vaccines have an excellent safety record and adverse reactions are very uncommon.
To date, there is no data available to provide information on the true incidence of adverse reactions to vaccines in companion animals, although we know that genetics, breed, size of the animal, and the number of vaccines given at one time may play a role. For this reason, we may recommend that if multiple vaccines are indicated for a certain pet, we want these vaccines to be given at separate visits to minimize this risk. Adverse reactions to vaccines include immediate anaphylactic shock, or less severe symptoms such as vomiting, diarrhea, facial swelling, or hives from a few hours to a few days after vaccines. If any of these symptoms should occur, please discuss this with our veterinarian.