How old do yo have to be to walk a dog?

A kid is allowed to walk a dog at age 4 as long as a adult is around. But if adult is not around then you have to be 10 and up to walk a dog. But if is a big dog then you must be 12 and up. But if it is a very little dog and if a parent is around then you can be 1 and up to walk the little dog.