There are many signs a dog gives off to indicate how they are feeling. The main three aspects to look for are:
Ears: Up/forward - alert Back - submissive, cautious Flat, back - fearful/defensive
Mouth: Open mouth - relaxed Closed mouth, repetitive behaviour, like licking, panting or salivating - possible tension Snarled/Showing teeth/Barking - Aggression
Dog tail High quick wagging tail - aroused/excited Neutral tail, relaxed wag - alert/attentive Low tucked tail - stressed/fearful Neutral tail - relaxed
Be aware of the environment a dog is in and their feelings around it. If you are in an environment they have not been to before, allow them time to acclimate and move at their own pace.
The fastest way to create an issue is to force a reaction from a dog who is feeling unsafe or overwhelmed.
Dogs in crowded and over-stimulated situations may be hard to read properly and can react in an instant.
Be sure to make all dogs feel comfortable and safe, avoid cornering any dog to reduce the likelihood of incidents occurring.