It's a given fact.
Dogs are like humans, and they become bored.
If not kept stimulated in their environment, they will look for something that will give them hours of play. This unfortunately happens to be your furniture, shoe, the leg of a chair or table, etc. The reason dogs chew is mainly our fault, since we don't give them enough toys or don't have time to give them our undivided attention. Most families today work outside the home and therefore spend less time with their pets. The ultimate price is coming home to find that your pet has chewed a hole in your sofa or has eaten your favorite shoe.