Every dog is an expert at reading body language. You and your dog probably pick up on each other's signals without thinking much about it. But if your dog begins to behave differently, it helps to be able to read the universal body language of dogs.

If you and your dog landed in Tokyo or Timbuktu tomorrow and were greeted by a local person and his dog, it would take only a few minutes for the two dogs to understand each other. Hours later, you would still be wondering if you were bowing properly, making acceptable hand gestures, or using the right table manners.

A dog wags his tail when he is happy or wants to play or is expecting something enjoyable - like a treat or an adjustable dog feeder filled with food. It is really an energy indicator. When he is submissive, he tucks it between his legs. A taut tail, held down rigidly behind him, may show that he is prepared to spring since he uses his tail for balance when jumping.

A wagging tail tells everyone that the dog is excited, alert and aware of what's going on around him or her. Tail wagging is a learned expression. If you've ever been around puppies you'll notice that they don't wag their tales until about 1 month old and by 1 1/2 months, all the puppies have started wagging. By then they've learned to use this appendage as a sign to others that they are content with the world they see in front of them. They learn this skill from observing their mother and how she interacts with other dogs and how she interacts with the big humans as a way of getting along with these giants.

How high or low the tail is held, in relation to how the dog's breed naturally carries their tail, and how it is moved can signify the dog's mood or rank. The higher the tail is carried, the more dominant/confident the dog is; the lower, the more submissive/insecure. A tail held straight up, or even slightly curved over the back, shows that the dog is very dominant. If the fur on the tail is also bristled, the dog is saying they are willing and able to defend their position. Small, slow wags of the tail says the dog is questioning things around them. Either they aren't sure if the target dog or person is friendly, or they aren't sure what is going on or what is expected of them

Large, fast wags of the tail is a sign of a happy or excited dog. If the wags are large enough to pull the dog's hips with them, the message includes a bit of submission to someone they view as pack leader. Dogs with docked tails, like Dobermanns, tend to have some problems communicating with other dogs, since their tail movements are extremely difficult to detect. Dogs with docked tails will usually compensate for this by wagging their entire rear end.

Recent research has suggested that left-right asymmetry of the tail wags is likely to also convey information along the approach/avoidance axis.