Feline injection site Fibrosarcoma is a type of terminal cancer related to inflammation caused by rabies and leukemia vaccines.(12) This cancer is thought to affect 1 in 20,000 cats vaccinated. Mean disease free interval time or survival time with surgical removal is about 3 months. Mean survival time with surgical removal plus radiation treatment plus chemotherapy is less than 3 years. Amputation of a rear leg plus radiation has resulted in a few cures.
Vaccines with adjuvant, an ingredient included to stimulate the immune system, have been implicated as a higher risk, although other injectable drugs have been incriminated as well. Adjuvanted vaccines have been demonstrated to induce mutation in cell cultures. Adjuvanted Rabies, Distemper and Feline Leukemia vaccines have been classified as Class II carcinogens by the World Health Organization.
To minimize the risk of injection site fibrosarcomas, we now recommend all non-adjuvanted vaccines for cats, including Merial PCR Purevac rabies vaccine. Testing by Dr. Dennis Macey, Colorado State University, has shown this vaccine to have the lowest tissue reaction. Although there is no guarantee that an injection site fibrosarcoma will not develop, the risk will be much lower than with other vaccines.(12) After three years on the market there have been only two injection site fibrosarcomas confirmed with Purevac rabies vaccine vs. over 70,000 caused by adjuvanted rabies vaccines.
Cats over one year of age are naturally 89% immune to FeLV (age related resistance) whether they are vaccinated or not, so annual vaccination of adult cats is not necessary.(10, 15-p5, 21-p681,23-p239) Age related immunity is actually better than vaccine induced immunity
The duration of immunity for Rabies vaccine, Canine distemper
vaccine, Canine Parvovirus vaccine, Feline Panleukopenia
vaccine, Feline Rhinotracheitis, feline Calicivirus, have all been
demonstrated to be a minimum of 7 years by serology for rabies
and challenge studies for all others.
Schultz, Ronald D, Duration of Immunity to Canine Vaccines: What We Know and What We Don’t Know, Proceedings – Canine Infectious Diseases: From Clinics to Molecular Pathogenesis, Ithaca, NY, 1999, 22.
Minimum Duration of Immunity for Canine Vaccines:
Distemper- 7 years by challenge/15 years by serology
Parvovirus – 7 years by challenge/ 7 years by serology
Adenovirus – 7 years by challenge/ 9 years by serology
Canine rabies – 3 years by challenge/ 7 years by serology