Dog body language can be very subtle. Many people may not realize a dog is stressed until he escalates to growling. Other signals may be misinterpreted as defiance, dominance, and ignoring us. In reality the dogs are often confused and stressed. They are trying to let us know what is going on and we do not understand. Alternatively we may react in ways that escalate the situation instead of diffusing it.
Look at the following images for some subtle stress signals.
Here is the same dog showing more relaxed facial expressions.
What are you seeing in this dog?
Ears back, lip lick, hard to see but she is leaning back.
What about now?
She is attentive and curious.
Now, watch the following video and see how many stress signals are missed and how the trainer responds in ways that increase the risk.
The Safe Kids/Safe Dogs Project