An Instinctive Behavior Most behaviors of dogs are either the product of instinct or a learned behavior. In addition, there are certain breeds, terriers and dachshunds, for instance, which were bred specifically for their ability to dig out game such as badgers, foxes, and otters. They have an even greater digging instinct.
Dogs dig for a variety of reasons.
Dogs will often dig out of boredom. If you leave your dog out alone in the yard for any length of time, he may dig just for something to do. Play with him out there or provide him with chew toys or interactive toys like a Kong or Pet Planet rubber toy with treats stuffed inside. Digging is often used as a means of escape. Your dog may want to leave a fenced yard because there are so many more interesting things to do elsewhere.