A dog can express more with his tail in seconds than his owner can express with his tongue in hours. ~Author Unknown
I've always considered a dog's tail, and it's carriage directly connected to the dog's mind. So much information can be gleaned from watching the dog's tail... provided of course one can "read" his dog.
Positive and negative emotions can be clearly recognized. The "merry" tail, working and crackin'.. what we all like to see.. The fearful tail, tucked.. The "not at all feeling well" tail, carried low and listless.
Everyone recognizes the happy, wagging tail of a dog.. but a responsive owner/ handler can tell so much more, even up to the point of workin' a bird and just what species that bird may be.. The dog's nose is tellin' him, and that dog's tail action is tellin' you.
Dogs are such simple creatures, but at the same time very complex.. All we have to do is observe and learn from them..
They have so much to teach us!