You can understand a lot about your canine companion from his dog tail signs. That wagging or thumping on the carpet? You know your pup is feeling great. That feeling of dread when you walk through the front door and that same tail is tucked low? That tail tells you something has been destroyed by a bored pup while you were away. Whether you consider yourself fluent in wag or you're still learning how to decode dog tail language, read on to learn more about how your pet communicates.

Spotting the Signs: A Guide to Dog Tail Language

A dog's tail originally evolved to help him stay balanced, like a tightrope walker's pole. It serves as a counterweight to the front part of his body when he's making a high-speed turn while hunting and helps keep him from falling off narrow walkways.

Now that a dog hunt generally involves finding the last piece of kibble that fell behind the bowl, that wagging tail is largely thought of as a communication device. Here are five key things the placement of a dog's tail can tell you, according to the Center for Shelter Dogs at Tufts University Cummings School of Veterinary Medicine.

1. Circular swish: A dog whose tail is swishing back and forth or in a circular motion is one happy and relaxed pup.
2. Lowered or tucked tail: A dog who is frightened or feeling submissive will often lower or tuck his tail between his hind legs.
3. Tail wagging stiffly: A dog who is excited may wag his tail stiffly while jumping, spinning or sticking his rump in the air. His excitement may be from a positive source like an upcoming walk or a negative source like an intimidating stranger.
4. Tail held horizontally: A tail held straight out indicates a dog who is attentive and alert or perhaps curious about something nearby. Traditional hunting dog breeds like pointers or setters also hold their tails out straight when they point at an animal or object.
5. Sudden tail raise: When a dog moves his tail from a down position to a vertical or raised position, it could indicate he is feeling aggressive.