By standard intelligence texts, the dogs have failed at the puzzle. I believe, by contrast that they have succeeded magnificently. They have applied a novel tool to the task. We are that tool. Dogs have learned this--and they see us as fine general-purpose tools, too: useful for protection, acquiring food, providing companionship. We solve the puzzles of closed doors and empty water dishes. In the folk psychology of dogs, we humans are brilliant enough to extract hopelessly tangled leashes from around trees; we can conjure up an endless bounty of foodstuffs and things to chew. How savvy we are in dogs' eyes! It's a clever strategy to turn to us after all. The question of the cognitive abilities of dogs is thereby transformed; dogs are terrific at using humans to solve problems, but not as good at solving problems when we're not around.
Alexandra Horowitz, Inside of a Dog: What Dogs See, Smell, and Know
animal-intelligence, dogs