Ask the average person how to tell whether a dog is happy, and they will advise you to look at its tail -- if the dog is happy, the tail is wagging.

Unfortunately, this is only partly true. Rapid tail wagging, where the side-to-side swings are not very large, is actually a sign of excitement rather than pleasure. It is when the 'ail wags broadly at a moderately fast rate that the dog is trying to say either "Iím pleased" or "I like you."

Some tail wags have totally different meanings. A slight wag with the tail held at its normal height, for example, usually appears when greeting someone. It can be interpreted as "Hello there," but can mean "I see you looking at me. You like me, donít you?"

A slow wag with the tail held lower than its usual height is a sign of insecurity. It often shows up when a dog is working on a problem -- trying to understand what is going on. During dog training, I interpret this signal as "Iím trying to understand you. I want to know what you mean, but I canít quite figure it out." Once the dog finally solves the problem, the speed and size of the tail wags will usually increase until it becomes the broad wag that we interpret as happiness.