ok, so if it's not separation anxiety, it could be anxiety in general(non-specific). OR it could be neurological like obsessive compulsive type of disorder.
Regardless of the cause, I would talk to your vet about this being more neurological / habit type behaviour after of course, allergy tests have been ruled out! If there's no medical problem, chances are it's a behavioural problem. Boredom maybe???
Silly question: Does she have chew toys or bones to chew on? And does she get enough exercise??
Never mind the dogs, beware of the owner!!!