My guess is he is just bored. Normally they slow on the chewing around age two. Perhaps a little kennel time when you are not around would do him some good? I have a few dogs as well and though they play together a lot they all make time to be a pest at some point. Give him some good hard work a few times a day, see if that helps. Not just ten minutes of fetch but real work, a solid 1/2 hour swimming followed by some work wear him down a bit. I know at 100 lbs he will tire (it may take a bit but he will). I have a GSP that hunts all day everyday. The Wife hates it when she leaves snakes on the porch (the snake hunting thing is not good as we hunt in eastern WA in the early fall and I do not want to deal with that), we had a mouse under the seat of our quad one day and she removed all the soft parts of the seat and wiring to get at it
. She is no longer allowed in the shed, my fault but she knows to stay out now. We now spend more time with them (working) and it seems to be helping.
