There may be something in the vaccine media that is actually leading to the sarcoma in cats.The bottom line is that tumors are found more frequently where vaccines are given. Sometimes the material used in a vaccine is actually found in some cat tumors. It’s all fairly hard to investigate because of the time that passes between the vaccination and when the tumor is discovered.A vaccine associate sarcoma is a tumor that develops at the site of injection of a vaccination. It’s not known what causes the tumor; if it’s the vaccine or a substance mixed with the vaccine to encourage a stronger immune reaction that causes it.It was if cat’s where getting cancer, but dogs didn’t. Cats that have experienced an injury to the eye have a greater chance of developing a sarcoma in the cat’s eye. Why dogs don’t have this problem, but cats do may be related to the type of vaccine?In the 80’s the feline leukemia vaccine became available. About the same time several states made rabies vaccinations mandatory. Veterinarians naturally gave the vaccines at the same time, usually in the same location on the cat’s body.After cats started showing up in vet offices with tumors and vaccine associated sarcoma was suspected, vets started to move the injection spot to a different location for each vaccine. This would also help identify if a feline cancer was related to a vaccine location.The Vaccine Associate Feline Sarcoma task force recommend that the rabies vaccine be given in the right rear leg, the leukemia vaccine in the left rear leg, and all other vaccines off the shoulder midline area. There was one other recommendation. One opinion is to only vaccinate your cat with vaccines she needs. If you cat is a completely indoor cat, then there little risk of feline leukemia and she probably doesn’t need that vaccine.There was one more recommendation that is most controversial. That recommendation was to give vaccinations less frequently. Vets are not so much concerned that a vaccine will ‘wear off’ if it’s given less frequently than they are that cat owners won’t bring in their cat to the vet for its annual wellness exam. There are known limitations in this system, such as the variable quality of data, variable reporting (both under reporting and stimulated reporting). This also fails to assess the link between cause and effect. Despite these limitations, this system is the best available and can be accessed by all concerned.Out of more than 28 million doses of this vaccine given as of January of 2010, 16000 episodes of adverse events were reported to VAERS. Over 90 percent of them were not serious events and included irritation at the site of the injection, nausea, headaches and fainting episode, especially in the adolescent age group. It is recommended that the patients be vaccinated while they are sitting and observed for about 15 minutes for fainting spells before being released.Regarding serious events that were reported, the most common was an entity called Venous Thrombotic Events (VTE). "Blood Clot in veins" in simple language! Investigations of these events showed co-morbid conditions such as obesity, oral contraceptives, smoking and other contributing factors that could explain these thrombotic events.