A family member has a young shih tzu (now a year old). She got her when she was about 12 weeks old, she gets on well with the other dogs, she is affectionate, friendly, brave and very naughty. She is not left alone very often but at night and in the short periods when her owners are out she is left in her cage. The problem is that she chews the carpet, she is very quick and in just a couple of minutes she can do quite a lot of damage. She is not bored, she has lots of exercise and she loves games and play, she just has the devil in her. Any ideas on how to deal this please?