As we all know, humans and dogs don't speak the same language so dogs express their emotions and intentions through their body movements. From their posture and behavior, they are trying to tell you or another animal something. We just need to know how to read and understand them. Each part of their body sends a message from their eyes, ears, mouth, hair, head, body posture and tail. A couple examples I will give are eye's and mouth and what to look for.
When looking at a dogs eyes you may notice that sometimes their eyes get super big and have this white part all around it called the sclera. This "big" eye has also been known as "whale eye's". What does this mean? Well, the intensity of the dog staring at something or someone along with the whale eye's is a sign your dog is either fearful or aroused. This meaning that your dog may feel threatened, stressed or frightened. Dilated pupils and a glossy eye can also been a sign the dog is stressed or aroused. If a dog is calm and relaxed, they will have more of squint to the eyes with no white showing at all with a relaxed, calm face.
What to look for with your dogs mouth for signs of relaxation and signs that they are uncomfortable. If a dog is relaxed, they will more than likely have there mouth open, panting with their tongue out with no facial tension. If a dog is uncomfortable or scared, he will usually keep its mouth closed but also may be panting heavily. If a dog is panting and all of a sudden closes his mouth due to a change in the dogs surrounding, could be a sign of stress. If there is no food or toys around and the dog is drooling heavily may also a sign of extreme fear or stress. Big warning signs are the dog lifting his lip up to growl and or show teeth, and you will also notice a tense stare with whale eyes and a stiff, wrinkle head. If your dog is yawning and licking his lips a lot that is also a sign of stress, some dogs may also whine or have a tight mouth.
These are just a few signs a singles your dog is trying to give when expressing how they feel. Other parts of the body also play a key factor in all this as well. It is not usually just one "signal" they are giving off, their entire body sends a message. If a dog is giving the "whale eyes", you will also probably notice a hard, intense stare, with their body being extremely still, other wise known as "freezing". They may also have a slight growl or bare teeth. Not all signals are the same and not every dog will show all of these at once. Some may only display a few of these, so paying attention to their entire body and the environment going on around them is important and plays a factor. As you get to know your dog, will you see how they show their emotions and how they react. Not all dogs are the same, but start to learn and understand more of what your dog is trying to tell you or someone else, will also help build a better relationship between the both of you.