A Guide to the Secret Language of Dogs

Watching your dog interact with other dogs can be confusing. Are they playing? Are they fighting? Are they trying to tell each other something?

Marc Bekoff, a biologist at the University of Colorado, has spent decades studying the behavior of dogs, coyotes and wolves. By analyzing videotapes frame-by-frame, the author of "Animal Passions and Beastly Virtues" has discovered that there is a rich, unknown language that dogs use to communicate.

Here are Beckoff's tips on how to read common dog signals. Often, what you first assume you are seeing turns out to be the wrong interpretation:

Play Bow: This common posture, a building block of dog communication, means let's play. But it can also be a sign of an apology. It can be a dog's way of saying: "I didn't mean to bite so hard. Let's keep playing. I wasn't trying to be mean."

Paw Slap: This is like a human coming up and slapping you on the back. It looks almost comically stiff, but it's really a dog's caress, a way of saying: "Let's have fun." It puts the dog at an awkward angle, so it's a sign it trusts the other dog not to attack.

Hind-Leg Rearing: When dogs rear up on their hind legs, they look like two grizzly bears fighting. But, it's actually a sign of affection -- more like dancing. If the dogs wanted to fight, they'd use their jaws, not their forelegs. It takes a lot of coordination for dogs to do this together, but it's fun.

Biting: You see the fangs flashing and the jaws snapping, and you think it's fight time. But, once again, they're playing, and it's a sign of trust. Although the movements look random, they're not. Dogs are always careful to avoid the sensitive areas, such as lips, eyes and nose.