Dogs are said to be human's best friends for a number of reasons. These pets are kind, devoted and friendly, besides they are easy to train and always ready to protect you when necessary. Big and small, fluffy and short-haired, deep-voiced and squeaky - all of these dogs make equally great friends. However, these four-legged creatures have much more interesting secrets we never think about which can easily make you drop your jaw. Sounds unreal? Watch this lesson of dog science and make sure your dog is not listening to it!