PS: Please note that this is all scientific research-based and we may or may not approve. Simply put, we prefer to keep our old believes, a wag simply means: I WOOF YOU.

Perhaps the most common misinterpretation of dogs is the myth that a wagging tail is a sign of happiness. Yes, while some wags are indeed associated with joy, others can mean fear, insecurity or even a warning to stay away. In some ways, tail wagging functions similar to a human smile, a polite greeting or a simple nod of recognition. Smiles are social signals reserved mostly for situations where others (that includes dogs) are around. Unless you are one of the few people smiling and laughing to yourself... Since tail wagging is like a signal, normally a dog will only wag its tail when other living beings or moving objects (like a leaf in the wind) are around. Like any other language, tail wags have their own vocabulary and grammar. Until now scientists focused on two major sources of information, namely the tail's pattern of movement and its position. However recently another discovery was made: Movement by itself. Dogs' eyes are much more sensitive to movement than they are to details or colors, so a moving tail is very visible to other dogs. Evolution has made tails even more visible, such as tails with a light or dark tip, a lighter underside or a bushy shape. The tail's position, specifically the height at which it is held, can be considered a sort of emotional meter. A middle height suggests the dog is relaxed. If the tail is held horizontally, the dog is attentive and alert. As the tail position moves farther up, it is a sign the dog is becoming more threatening, with a vertical tail being a clearly dominant signal: "I'm boss around here," or a warning, "Back off or suffer the consequences." As the tail position drops lower, it is a sign that the dog is becoming more submissive, is worried, or feels poorly. The extreme expression is the tail tucked under the body, which is a sign of fear: "Please don't hurt me." Just as there are different dialects to a human language, such as a southern drawl or a New England twang, there are also dialects in dog tail language. Different breeds carry their tails at different heights, from the natural nearly vertical position common to Beagles and many Terriers to the low-slung tails of Greyhounds and Whippets. All positions should be read relative to the average position where the individual dog normally holds its tail. Movements give additional meaning to the signals. The speed of the wag indicates how excited the dog is. Meanwhile, the breadth of each tail sweep reveals whether the dog's emotional state is positive or negative, independent from the level of excitement. As a result, there are many combinations, including the following common tail movements: ● A slight wag, with each swing of only small breadth, is usually seen during greetings as a tentative, "Hello there," or a hopeful "I'm here." ● A broad wag is friendly: "I am not challenging or threatening you." This can also mean: "I'm pleased." This is the closest to the popular concept of the happiness wag, especially if the tail seems to drag the hips with it. ● A slow wag with the tail at half-mast is less social than most other tail signals. Generally speaking, slow wags with the tail in neither a particularly dominant (high) nor a submissive (low) position are signs of insecurity. ● Tiny, high-speed movements that give the impression of the tail vibrating are signs the dog is about to do something, usually run or fight. If the tail is held high while vibrating, it is most likely an active threat. We can now add another newly discovered, feature of dog tail language that may surprise attentive pet owners as much as it surprised scientists like me. It now appears that when dogs feel generally positive about something or someone, their tails wag more to the right side of their rear ends, and when they have negative feelings, their tail wagging is biased to the left. Giorgio Vallortigara, a neuroscientist at the University of Trieste in Italy, and two veterinarians, Angelo Quaranta and Marcello Siniscalchi, at the University of Bari published a paper describing this phenomenon in the journal Current Biology. The researchers recruited 30 family pets of mixed breed and placed them in a cage equipped with cameras that precisely tracked the angles of their tail wags. Then they were shown four stimuli in the front of the cage: their owner; an unfamiliar human; a cat; and an unfamiliar, dominant dog.