Q Why do dogs wag their tails?

A The tail is much like the hands for humans, a way for dogs to communicate and express themselves. There are also other body parts that dogs use to help to express themselves, such as the ears and the eyes, the position of the head, and the hackles. But when it comes to the tail, there are actually different wags that mean different things. Though a tail wag is usually thought of as a friendly sign, that's not always the case. A dog who is showing that he's friendly may loosely wag his tail, while dominant or aggressive dogs will hold their tail high and rapidly wag just the tip of the tail. Submissive or scared dogs will hold their tail low and stiffly wag it, while playful dogs will hold their tail high but wag it with great swoops from side to side.