Dog is the most faithful friend to human, very clever, particularly in its sensitive nose. The body of some kinds dog higher than a 8-year old child and some shorter than a cat. Sometimes, people play with them, and teach them dozens of fun tricks in the park.
It is the good helper to people, such as watch door, hunt, lead the way, performance etc. The dog has strong protection to its master, some news has reported, dogs from water and fire house to save the child.