Both Fergus and Callum are furniture chewers, even though they have tons of chew-y appropriate snacks. I think its the eye level quality of my desk and my Dad's dresser that made them so appealing.
I wanted something I knew was edible, but would deter them: I used hot sauce. Neither of them likes it, but it didn't hurt them. just disuaded them from doing it again! I took a dab on my finger and rubbed it on all the open wood (where he took off the finish!)
and they NEVER went back to it.
My Dad tried the same....but make sure its a REAL hot sauce, not like a spicy barbeque or wing sauce. (My Dad used ZING sauce first, and Callum LOVED it! LOL), but once we went to tabasco (Or chahoula, at our house) they stopped immediately! And it was right there in my cupboard, no expense, no trip to the store!