A cat would bite humans if the affection she is receiving has gone on too long, if she is playing or if she is unhappy about a situation. Biting also occurs when cats are protecting their territory or when a mother cat is protecting her kittens.
Kittens who are not handled properly between the ages of five and 12 weeks old may bite if they are frightened of humans. Some diseases, such as arthritis, can cause a cat to bite as well. Some cats bite because of their natural hunting instinct or if they do not recognize the scent of another pet.