Dog calming signals are communicated through body language, since dogs can't speak to one another. It's important to understand these signals so you can detect when your dog may be nervous or attempting to calm another dog. If you have a nervous dog, remember to reward all of these calming signals so he understands that you appreciate his calm behavior.
Sniffing
Dogs sniff all the time, especially if you have a hound breed. In fact, all dog calming signals are imitations of behaviors they often use for a purpose. The key to recognizing if your dog is just sniffing or giving a calming signal is the context of the behavior. If it seems out of context ("My dog never sniffs when he's playing with other dogs!"), it's a calming signal.
Dogs use sniffing as a displacement behavior to stall the interaction and allow the other dog or person to calm down. It works effectively, because even aggressive dogs can be displaced with this sniffing behavior.
During training, if you notice your dog sniffing rather than looking at you, consider whether you're moving too fast or getting too annoyed. If so, your dog may not be ignoring your commands, just trying to calm you down. Take a break and try again when you're happy.
Sitting or Lying Down
Dogs exhibit this behavior all time. However, if your dog suddenly stops playing and drops into a down or a sit, he is saying that the play is getting a little too rough for him and he would like a break. Most dogs respect this reprieve and wait for the other dog to get back up. If not, consider holding the other dog back a minute to honor your dog's break.
Lip Licking
Though you might not notice, your dog often licks his lips to signal a human or another dog to calm down. Though not as dramatic as dropping into a down or sniffing, it sends the same message to opposing dogs.
Many times, reactive dogs use this signal to calm down an approaching stranger or dog. Owners believe their dog's attack "came from nowhere" but he was actually signaling for several minutes before resorting to barking or growling. Be aware of this signal.
Yawning
Try yawning. It stretches you out a little and can actually be very relaxing. The same is true for dogs. Dogs often yawn to calm others and themselves. A yawn could mean, "I'm nervous" or "You're making me nervous." Either way, if your dog is yawning excessively, it's not because he's tired. Try to reduce the stressor at this time.
Averting Eyes
Since holding a hard stare is a sign of dominance, many dogs use averting their eyes as a signal that they would like to avoid a conflict. This causes them to look away and lower their body posture. When owners say, "I know my dogs knows he was bad because he acts guilty," they are referring to this posture. However, your dog doesn't know what he's done wrong. He's trying to calm you down.
Shaking
When dogs are wet, they shake their whole body to remove water. However, you sometimes see this behavior when they are not wet. This is a behavior that, like yawning, calms them and sends a calming signal to whomever is making them nervous. You will often see this behavior after you bring your dog home from a stressful situation.
Always reward this behavior so your dog knows you value his calming signals. This will help him calm down in the future.