It is very incorrect to assume that pet cats, if kept within the house in clean care, do not require vaccination. Diseases are not always external. Though for a pretty long period the kittens keep receiving a type of antibody through mother milk, its effectiveness wears off at some time. Thus, the risk grows higher for the little cats to contact diseases from outside and let diseases grow inside them. So, vaccinating your pet cat is a must; otherwise, it may cost its life.