Vaccines have protected millions of animals from illness and death caused by infectious diseases. All medical procedures, however, carry with them some risk. Fortunately, in the case of vaccination, serious adverse responses are very infrequent. Veterinarians minimize risk by carefully selecting vaccines on the basis of a pet’s individual needs and by choosing appropriate injection sites. In an effort to find ways to prevent even these limited numbers of adverse responses from occurring, the AVMA is working with government and industry to redefine how information regarding adverse responses is gathered, analyzed, and disseminated.