shih tzu digs in bed only

Question
Our Shih tzu Millie is a great dog--at night before she goes to sleep she digs in her bed till she is out of breath.  It is so funny.  Is this frustration or natural for dogs??  She does not dig anywhere else, just in her bed.  What do you think??

Answer
Sorry for not getting back sooner, AllExperts was down for a bit.
I think the behavior is completely natural for your dog. Maybe try excersizing her a bit more before bed so she doesn't do it as muc(of course only if this bothers you). Otherwise, just let her have her fun.
Digging is a wolfs way of making a bed. Sled dogs also do this and so do some pets. As you've noticed in Millie. My akita used to do it in the summer outside when he was too hot. The cool ground helped him cool off.
So as long as Millie is in good health, there is nothing to worry about.

Emily