A dog has senses that humans do not. Dogs navigate their world predominantly by smell. Even though their brain is one-tenth the size of humans', the part that controls smell is forty times larger than in humans. Depending on the breed, their sense of smell is about one thousand to ten million times more sensitive than a person's nose. Did you know that the mucus on the nose of a dog helps them to capture scent particles? There are some studies that use dog olfactory senses to determine the presence of cancer-causing diseases by smelling human urine. In the majority of these tests performed by the dogs, they were accurate every time. Watch the video to see how this dog hilariously sniffs out his favorite treat.