One of the things you might love about your pet pooch is that his actions are straightforward -- what you see is what you get. Although that often is true, it doesn't mean that doggie body language is always plain as day. While tail movement often indicates joy in canines, there are definitely important exceptions.
Amiability
If your dog softly wags his tail at the sight of you, it often means that he's in positive spirits. The cutie is delighted to see you, and is expressing it in the most sincere -- and adorably canine -- manner. Content dogs frequently wag their tails in circular, wide motions. They also usually maintain their tails at the same elevations as the rest of their physiques. This wagging often is an invitation for together time, whether through cuddly petting sessions or play.
Esteem
Tail wagging that employs the hips can be an indication of esteem and admiration. If your dog does this, he looks up to you -- and wants you to know it. If you ever need to discern between this kind of wagging and classic "giddy" wagging, glance over at your pooch's hip region.
Truculence
Although the polar opposite of esteem and delight, tail movements can sometimes denote truculence in dogs. If a dog is upset about something -- and is possibly even on the verge of fierce behavior -- he might elevate his tail and harshly and rigidly thrash it from one side to another. This wagging is often referred to as "flagging," and frequently entails rapid, sweeping motions. Angry dogs also often display quivering tails. Leave a dog alone if you ever notice any of these tail actions.
Uncertainty
If a dog moves his tail in a measured manner while maintaining a tight posture, it often signifies uncertainty and confusion about the present circumstances. The pooch just isn't sure how to proceed with whatever is going on in front of him. Do not bother a dog displaying this body language.
Scent
Dogs sometimes use tail wagging as a way of giving off their individual identifying scents via the anal glands. This is especially prevalent in self-assured dogs with lots of confidence. Dogs who are meek and don't want to be noticed not only often abstain from wagging their tails, they frequently hide them by tucking them away under their back legs, as well.
Anxiety
Anxious dogs usually keep their tails much lower to the ground than normal. They sometimes wag their tails, but usually extremely swiftly. Dogs who feel vulnerable in the face of others with higher status also frequently engage in this kind of tail wagging.