I've rented a home for 4 years and my pet ate some of the carpet.
It's clearly damage and I do not mind paying a little of a prorated amount.
At what point does carpet and paint (become normal wear and tear and there is no life left in the carpet. Or paint that has faded and chipped....
I think normal life span for rental is:
carpet 5 years
paint 2 years
So I would expect to pay 20% of the replacement IMO for the carpet.