In a recent study, the possibility that dogs showed facial expression to the human.
Independent: Dogs are trying to communicate with us, even if we don't know it, new study suggests
In this study, researchers examine how the dogs react when a person looks at them. They showed particular emotions with making faces. Their actions were different from those when they find foods.
I am not familiar with this academic region. And I have not read the original article. Therefore, I cannot evaluate the validity of this hypothesis that dogs have facial expressions to tell their emotion to human. But, it is not surprising if they do, I think. Dogs are sharing several genes with humans. Also, I often sense some cats expressing their emotions according to each situation.
It is another issue whether dogs have each emotion we always feel. It is known some mammals play games with their friends. Also, apes are said to have the sense of equality. It seems that animals have emotions of joyfulness for entertainment and rage when being discriminated. They are quite human-like emotions.
On the other hand, how much are we understand their emotions? If we can share some emotions with dogs, new technologies will enable us to bridge each thought in the future.