While humans primarily use words to communicate, dogs use energy to communicate, expressing it through body language. To communicate with our dogs, we need to learn and adopt their 'language' rather than expecting them to learn ours.
One way to decode a dog's language is to remember that Energy = Intention + Emotion. A dog's energy -- his intention and emotions working together -- are communicated by his body language.
A dog's play bow to another dog illustrates how this works. The motion is forward, but the front of the dog's body is low to the ground. The intention (the forward movement) is excitement but the emotion (the low body) is friendly, so the energy is playful.
Similar behaviors can mean different things. For example, a happily excited dog and an aggressive dog may both move forward toward a person or other animal ' but one of them is playful and the other one is threatening. Likewise, a dog may run away in fear or it may run away to start a game of chase with another dog.
The important parts to watch are the head, ears, tail, and back. The higher these are, the more dominant a dog is feeling, and the lower they are, the more submissive or uncertain her feelings. Look also for tension in the dog's body, particularly in the back and legs. The more tense a dog is, the higher its energy level.
It can be easy to misinterpret a dog's energy. So develop a habit of close observation of their body language. For example, many people are afraid when a dog shows its teeth ' but an astute observer knows that when the teeth are together, with the ears pulled back along the head, eyes squinting, and the body is lowered and leaning away, the dog is actually showing submission. Likewise, a dog may come charging at you, but if its body is relaxed, its tail is level and wagging, and there's no tension in the body, then it is showing excitement, not aggression.
Dogs can't tell us in words what they're thinking and feeling because they don't have to. They're expressing themselves constantly through body language. Once we learn how to understand this, a whole world of communication with our dogs opens up.