As pack animals, dogs have developed vocal sounds, as well as body language, to communicate with each other. Canines that live and hunt together in a pack must be able to communicate if they are going to feed themselves, rear their pups, maintain their territories and establish their dominance within their pack. Dog parents must teach their young how to survive and their pups must listen to their parents’ lessons. A male must know how to use body language to defend his place in the pack without having to constantly fight to maintain his position. As a social unit that hunts in a group, dogs must be able to signal an attack and to understand when to move forward and when to stay back. Inter-pack warnings are necessary if an intruder is near.
The dog's vocal sounds (barking, growling and whimpering) are the most obvious forms of dog communication. Although barking varies with size and dog breed, it can communicate everything from excitement to fear. It is believed that the characteristic baying sound of some hounds serves to communicate location to their straying pack members. The howl of a wolf serves the same purpose. Growling usually serves as an aggressive warning. Whimpering usually indicates a desire for attention.
In addition to vocal sounds, dogs use body language to express their thoughts and feelings. The position of the ears and the position of the tail can carry a strong message to other dogs and even humans. When a dog greets his owner, the tail wags and the ears perk up. In a situation where the dog feels insecure, the tail is tucked between the legs and the ears are lowered.
Most dogs will not bite without signaling the intention to do so, usually by growling and baring teeth. By following a specific series of gestures, a dog will communicate his desire to avoid or initiate a fight. A dog with an aggressive personality will relish a challenge, standing with the fur on this back raised, lips pulled away from his teeth and tail held high. A submissive dog will respond by turning away from the dog, tail lowered, or by laying down on his back with his paws up. Direct eye contact is avoided. Puppies will even dribble urine to signal their submission to a dominant dog or human.
Dogs also communicate with each other when they want to play. Known as a play bow, the instigator will drop down on his forepaws while leaving his rear end up. He will then leap up and dance around, wagging his tail and sometimes barking encouragement. The dog will repeat the body language when trying to play with a human.
A male dog will use urine scent markings to communicate his territory to other dogs. When a dog lifts his legs on all the trees and bushes in his yard (as opposed to just getting it over with in one place) he is mapping out the perimeter of his personal space. He will do the same when taking a walk through a neutral territory -- leaving notice to all other passing canines that he was there.