When working with a dog, communication is absolutely key.
Even when we are the same species and are speaking the same language, there are still disagreements, arguments and misunderstandings - you don't have to look very far on the internet to find people who will argue the opposite points on the same subject until hell freezes over.
But as humans, we love to think that we're right and everything else is in our control. How often do we hear that we're the dominant species on the planet, and we can do what we like?
So it's little wonder it takes some effort to recognise and understand the body language and intent of an entirely different sort of communication.
Just as every human (who speaks the same language) can have very unique ways of expressing themselves (just look at the breadth of regional dialects throughout any country in the world), each dog can have their own way of expressing themselves. Applying those blanket rules and ideas to every dog is a basic, but common, mistake.
We've touched on this in other posts, and in the section about communication; you need to watch and learn from the dog you're trying to help. There's no sense in trying a one-size-fits-all approach - you may get some parts right, and other parts disastrously wrong.
Many times we've seen people exclaim "those dog's are going to fight! LOOK!! Their tails are over their back!! Their ears are up!!"
Dogs also hold their tails aloft when they're flirting. They prick up their ears, and have a Pepe-Le_Pew sort of stance. It's not about focussing on one detail of body language, but looking at what the whole of their body is telling you.
Contrary to popular belief, one dog putting their head over another dog's body does not mean they are being 'dominant' or 'aggressive'. Again, this is a movement which occurs frequently in doggy flirting. But some books and television programmes have conditioned these people to be constantly on the alert for 'dominant' behaviour.
As soon as you pull a dog away from interacting like this, it often instigates a negative reaction from your dog. Some people take that as 'proof' that they were right to pull the dog away. In actual fact, pulling the dog away gives them the signal that there's something wrong, and they try to defend you - because that is message you're giving them.
We've worked time and time again with dogs labelled as 'aggressive' or 'dominant' with other dogs, and it just isn't the case at all. What you have is a dog who is following the exact instructions they are being given, it's just that the human doesn't understand that THEY are giving the wrong signal out in the first place...