had two dalmatians in the past and they decided to chew through a fire door to get out of the kitchen. they started at the bottom, we put lemon on it, vinegar, viks, salt, detterent, even a very thin coating of bleach next to where they chewed. did nothing. got in one day and one welcomed us with a head coming out from under the kitchen door. a foot tall, thick brass plate soon stopped them though. they were teething though and soon grew out of it. if its not teething i would say its boredom, possibly left alone too long and wants to get out to get to the rest of the pack. try leaving a radio on or something to keep doggie company during the day. a cage during the day will prevent your house being destroyed but i doubt it would make the dog feel any better, at night a cage should be fine as long as its comfortably big enough
lesson really, dont leave anything in range. those dalmations also managed to eat an entire sack of potatoes in an hour cos it was in reach.