My eight year old grey tabby, Jewel, began ripping out her back claws one by one with her teeth about a month ago. She has done this to all but two of her back claws, leaving only bloody scabs in place of the claws that she has ripped out. This is obviously painful because she screams whenever her back paws are touched. Does anyone know if this sort of self-mutulation is normal behavoir for cats? I just don't understand why she is doing this to herself.