Imminent Threat Barking This is one of the main reasons why dogs will bark. As dogs have an acute sense of hearing in addition to smell, they may be capable of sensing danger way before the owner is aware. And that is the reason why some owners love to own dogs such as Pitbulls or German Shepherds. These dogs are typically reared as guard dogs, as a result of assisting the owner to guard the family as well as the territory. However, sometimes, the dogs may bark at anything that seems to be a danger, including the milkman or even your friends. If this is common and resonates with you, you will then need to take steps and learn how to stop a dog from barking.