In an effort to reduce the risks of vaccinations, while continuing to protect our pets from fatal infectious diseases, the nonadjuvanted rabies and feline leukemia vaccines are now being used on our feline patients at Lyndale Animal Hospital. Both of these vaccines should be boostered on a yearly basis.  The city of Minneapolis requires all pet cats and dogs to be licensed and up to date with their rabies immunizations.

The feline leukemia vaccine is recommended in cats that go outdoors or are at risk of being in contact with cats of unknown disease status.

Vaccine site-associated sarcomas, a cancerous tumor that can form at the site of a vaccine injection, have been rigorously studied in veterinary medicine. In 1997 a Vaccine-Associated Feline Sarcoma Task Force (VAFSTF) was established to investigate this relatively rare, but aggressive disease, stimulate research and initiate changes in feline vaccine recommendations.

Although the cause for sarcoma formation in felines is not completely understood, experts currently agree that the tumors originate in areas where there is chronic inflammation. Chronic inflammation at the site of a vaccine injection has been linked to the use of adjuvants in vaccines. Adjuvants, like aluminum salts and gels, are typically used in inactivated vaccines to enhance the immune response to the antigens within the vaccine.

Scientific evidence suggests that in genetically susceptible cats, chronic inflammation from vaccine adjuvants can lead to a cascade of physiological events, ultimately causing certain cells types to transform into cancerous cells.

Studies have shown that vaccination with inactivated, adjuvanted rabies or feline leukemia vaccines are associated with increased risk of vaccine site-associated tumors in cats. This association does not exist with the feline distemper vaccine (also known as the Panleukopenia-Rhinotracheitis-Calici or PRC vaccine). Luckily, experts have developed nonadjuvanted vaccines that lower the risk of tumor formation in cats.

Ask us at your next appointment if you have any other questions about vaccines and their associated risks.