Harry's only 13 months old - so don't really know with Yorkies whether it's a 'whole of the life' thing!
All I do know is, with every other breed I've had - once the puppy teeth are out, the chewing generally calms down (thank goodness!
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I know you give her bullysticks etc, so offering the alternative is the best and most effective way to go. The trouble is, the 'scene of the crime' often changes once you've sprayed the bitter apple - so keep on keeping a close eye!! Good luck! Sally + Harry x