Suzy was telling me Indy (See Batman Indy) is due for his first rabies shot soon and it came to my attention that not every cat owner knows rabies vaccine can cause tumor in a small number of cats. I received a Vaccination Warning for Cat Owners from Especially Cats Veterinary Hospital in San Francisco during Minna's first check-up. According to this warning, approximately 1 in 10,000 cats can develop a cancerous tumor called a fibrosarcoma at the injection site of Feline Leukemia Virus (FeL V) and Rabies Virus vaccines. BTW, FVRCP or 3in1 vaccine will not cause cancerous tumor. Please discuss each cat's needs with its own vet but I think it is important to know about this uncommon complication. Again, always inform your vet of any pain, swelling, or lump found at the injection site of any vaccine.