1. The first sign you should always look for with a dog that may get to the point of biting or attacking is stress. It’s very easy to see if a dog is stressed just by reading the signs. The first is heavy panting when a dog hasn’t done any exercise. Drooling, ears pinned down or back, tucked tail and half-mooned eyes (showing the whites of there eyes) are all also indicators of stress. These are just a few though. There are many, many other indicators of stress like shaking, scratching, yawning, and cowering. Dogs displaying these signs will not attack unless they feel threatned as well as stressed but it’s always important to recognize these signs and figure out a way to get the dog to calm down. Even if that means you walking away. Also, you don’t have to be actual threat to be threatening to them. A simple hand movement towards the dog can provoke them to bite if they feel you are a threat.
2. These are more of the alert signs that might indicate a dog that would be willing to chase you down. Watch for alertness. If you see a dog see you and he/she tail and body gets stiff while their ears are stiff and back(not down) this is a sign that the dog is watching you and ready if you make a move they feel is threatening.
3. This is one of the most important signs, and if you ever see this it is very important that you get out as quickly and calmly as possible. It’s called the stalking stance. It indicates that the dog is watching you and probably will attack. This is easy to spot. A dog in the stalking stance will be stiff, body will be semi-crouched, tail will be lowered, and head will be lowered but this dog will not take it’s eyes off of whatever he/she is stalking. You see this in the wild frequently. A Cheetah will crouch down as be as quiet as she can, staring at her pray right before attack. If you see this stalking stance it means that this dog is not only ready for attack, they plan on doing it.
4. Bearing of the teeth. A very obvious sign that a dog is unhappy but you will need to see other signs of stress and or aggression to recognize this as a dangerous sign. Some dogs do, “smile,” which is them bearing there teeth but they only do this while they are playing or seeing someone they like. A dog, “smile,” will be accompanied with a relaxed, happy wag of the tale, relaxed ears and, most likely, jumping and/or bouncing.
5. This sign can be semi hard to interpret but nevertheless important. The resource guarder. This is a dog that will guard whatever he/she finds dear to them. Owners, food, a toy just to name a few. An example of an obvious resource guarder would be a dog that would hug their food bowl after they were done eating. If you came around them and the suddenly got stiff, showed the half moon eyes or showed their teeth it is very important that you remove yourself from the situation and get someone that can handle it appropriately.

It is very important that if you ever come in contact with a dog that makes you uncomfortable or scared, you need to stay calm. Dogs can read your body signs as well and they will feel and feed off of your stress. It’s also important to remember that each of the 5 signs can lead into eachother so it’s safest to see the beginning signs of stress or aggression so you can leave the situation safely.

Good luck out there.