We've identified seven general reasons for barking. Each generates a different kind of bark with a unique sound.

1. Barking to induce play. Dogs will stop barking as the play proceeds. If you do not play with the dog, he (or she) will eventually give up and stop barking.
2. Barking to discipline young. This bark generally does not persist, as one or two warnings usually stop younger animals in their tracks.
3. Barking to warn of danger. This is a deep, repeated bark. The barking will generally persist until the source of danger is removed or until the dog is able to retreat to a position of safety.
4. Barking to threaten intruders. To stop such a bark, you must either remove the intruder or remove the dog from the situation. Sometimes, stepping to the dog's side and assuring it that all is well will cause it to stop barking.
5. Curiosity barking. In general, this bark is displayed when there is some activity near a dog, but in such a place where the animal cannot have a good look. To stop the barking, all you have to do is let the dog see what it is curious about.
6. Barking for companionship. This is an incessant, repetitive bark, accompanied by a relatively motionless tail and concentration toward the area most associated with the dog's owners. The solution to this type of bark is to spend more time with the dog and to allow the dog access to the area where humans spend their time. This bark is often displayed by dogs that are ignored, tied out alone or locked up alone.
7. Barking for reward. Dogs can be inadvertently trainedto bark and will persist with remarkable persistence. Barking can become associated with almost any activity that leads to reward. For instance, a dog that barks at garbage trucks because they intrude within its territory will learn that persistent barking leads to the disappearance of the trucks. This rewards the barking behavior, and a cycle is begun that is difficult to break. To break the cycle, it is necessary to interrupt the natural system of reward.