Over the centuries dogs have been bred for a variety of tasks ranging from the close interaction of toy breeds with their owners to sporting dogs who require regular sessions of physical activity. Nordic dogs dig holes to cool themselves. Dachshunds were developed to chase badgers into their holes. Some dogs, regardless of heritage, may be more inclined to dig if they are left alone in the yard for long periods of time. Digging is often the result of boredom and this can be a learned behavior in some dogs.
Companionship is a primary reason for having a dog.
Being a companion means forging a bond through regular play and exercise with your dog. Without this stimulation, dogs often turn to digging or other forms of destructive behavior to alleviate their boredom. A dog that is pushed outdoors after it misbehaves in the house may continue its misbehaving by digging in the yard. Controlling your dog's behavior inside addresses that problem as well as unacceptable digging outside. A dog left alone may be reacting to the absence of family members.