Dogs have a developed instinct that tells them to hide in the lair. If there are no lairs around, the dog will build its own. One of the reasons why your dog digs in the garden is its genetic need to build a lair.
Some people condemn the owners, who put their dogs in cages. They believe that it is cruel and limits the animal's freedom. It is not true. Just watch the animal that was trained to sleep in a cage. This kind of dogs will always search for their cage when they feel tired, or want to be alone. Many owners leave these cages opened, so their dog can enter and leave the cage when it wants to. It is not a cage; it is some kind of small house for trained dogs.
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