If a dog's ears are back, it often means that he's frightened and expecting danger of some sort. Dogs differ from humans in that their ears are highly mobile. They're able to push them forward and back. They're even able to swivel them. Canine ears, as a result, are highly expressive communicative tools.
Fear and Submissiveness
Folded back ears are often a sign of fear in dogs. This ear position is an attempt to appear smaller. Folded back ears are often accompanied by other common fearful body language signals such as crouching, turning away the eyes and hiding the tail, all in attempts to appear smaller to potential threats. If your dog seems to be afraid of something, you can try to reduce his apprehensive feelings by acquainting him to it slowly and steadily. If your dog seems to be afraid of a person or fellow animal, try the gradual approach.
Relaxation and Playfulness
Although folded back ears can signify fear, they can signify the opposite, specifically calmness and playfulness. If a dog's ears are back as he jiggles his rear end and tries to solicit playtime from you, he's likely feeling at ease, happy and relaxed. When a dog has his ears pushed back just a tad, it's often a sign that he's feeling affable.
Raised ears in dogs are yet another sign of calmness. They also can indicate that a dog is listening.
Dogs who are at ease frequently carry their ears in natural and effortless manners.
Other Ear Signals
The levels of dogs' ears are important body language considerations. If a dog's ears are low, it usually denotes deference and lack of confidence. If they're kept high, it usually denotes dominance and superiority. The same goes for a high tail and head. If a dog's ears are high, he feels in control of the situation. If they're not, he's worried and feels doubtful.
Fully flattened ears, like low and pushed back ears, also often point to fear and submissiveness in dogs.
Forward Ears and Relaxation
Forward ears can provide valuable insight into how a dog is feeling. If a dog's ears are facing the front, he likely feels calm and confident. Other common indications of a relaxed dog include small pupils, relaxed muscles, slow tail wagging and soft panting that's unrelated to stress or excessive heat.
Ears that are pushed forward also frequently indicate vigilance in canines.