I’ve heard a lot of people saying “But his tail was wagging”. Humans have a hard time reading dog body language. Most think a wagging tail is always the sign of a happy dog. That is not the case. It is only a small part of a much bigger picture. You have to observe the whole dog before you decide if he is friendly, scared, anxious, aggressive, nervous, or just disinterested.
You need to look at their body tension. Are their legs stiff, is their mouth closed, hair raised, eyes so wide you can see the whites, barking or growling, avoiding eye contact, looking to make eye contact, tail tucked or straight up and wagging fast? These are all signs of the dog asking you to stay back…. Is it aggression not necessarily, but he is not comfortable and you need to stay back. He thinks you can read what he is saying, because if he displayed this to another dog they would get it.
A relaxed dog will have very little body tension his movements will be relaxed, his mouth with be open and he might even be licking his lips, his tail will be at a normal position for his breed, and it may move slowly or very fast but not stiff. His eyes will be soft.
We need to learn to see the whole dog. Dogs read each other so well, and they read us way better then we read them. If we can learn to read what they are telling us by simply slowing down and looking at them there would be a whole lot less of unexplained and unexpected bites and dog fights.