All dogs see in black, white and gray and also can see better at night than humans. When dogs sleep they curl up into a ball because it's more comfortable for them. Dogs have ten times better hearing than humans and they can smell something from one mile away. Most dogs are easy to train and most of them are very protective of their owners and territory. Overall most dogs are easy to train and most of them are nice to other people and dogs. Also all dogs are most playful when they are younger. Also all dogs can detect when a person have cancer or if they are sick. There are more then 700 breeds of dogs.