Bebe used to lick and chew on her backside until she had a huge bald spot on her hip. I couldn't figure out why she was doing this. At one of her vet check up appointments, the vet said it was not ring worm or any skin condition.
I did some research, and came to the conclusion that she must be itchy, so maybe she was eating something that she was allergic to.
By accident, I figured it out !
I bought her these at PetSmart. Pork and beef hides by SALIX. She loves these and dances around like crazy when she wants one. 
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Ever since I stopped giving her Hartz Dentists Best 5" twists, she stopped chewing on herself ! So, she must have been allergic to them !