Digging
Dogs that dig are not actually dogs with behavioral problems-they are dogs that are going on instinct. Dogs such as the Alaskan Malamute or the Siberian Husky are likely to dig in the dirt to make themselves a cool bed, especially during hot summers.
Dogs also dig for protection, storage, prey, and just for entertainment. Wild dogs dig dens to protect their young from storms as well as predators. Dogs also use holes as pantries or refrigerators-they catch and eat a big meal, dig a hole and bury the leftovers for later. They will also do this with their favorite bone, Kong, etc.,
Breeds such as terriers were bred to dig. That's how they find their prey-tunnel or den dwelling creatures such as badgers, moles and foxes. Cairn Terriers, Rat Terriers, Scottish Terriers, and Sky Terriers are built for digging.
Some dogs will dig just for the fun of it. The scents uncovered in the dirt excites the dogs, whose nose is much more developed that ours. A dog digging a hole in the backyard isn't a "stupid dog" that doesn't understand you don't want holes in your yard-it's a smart dog that has gotten bored. To prevent your dog from digging, keep the dog busy-physically and mentally. Take your dog for walks, go hiking in the woods, give your dog what he needs to keep stimulated- a worn out dog is less likely to run outside and dig a hole!
You may also notice that some dogs (especially terriers) will dig on their beds or on your furniture before they lay down on it- Some just paw at it gently, while others will be much more persistant at their digging. This is in their nature and it is doubtful that you will be able to stop this habit. If your dog is allowed on the furniture you may want to cover his spots with a dog bed or blanket so that when he digs it won't harm your furniture.