Separation anxiety manifests itself in a lot of different ways. Most dogs chew, some whine, some bark. The problem is that you usually don't know if your dog whines or barks unless the neighbors start to complain. Some dogs don't even show anxiety before you leave. They just get destructive in your absence.

If your dog is chewing when you leave and only when you leave, chances sound good that he has a bit of SA. Alone training will nip it in the bud, and you've really got nothing to lose