
Hiya
Yes, dogs do interact with one another on the grounds of who is the top dog and who isnt, status between dogs can change though adn in some situations one will be the 'boss' and in others this will change around.
When dogs meet each other, strangers at first, there is a lot of natural instinctive body language that goes on. In very small puppies, their reaction to an older, more mature dog, is to roll on their backs, and sometimes to pee.
Thats a natural appeasing gesture that means 'i am not a threat, i accept you as superior'. As they get older they learn from other dogs, so if your pup was to always play with dogs who liked rough fast chase games, for example, and had no problem with bottom nipping whilst chasing (my two lurchers do this) then the pup learns that this is fine. You then can get a problem when the pup meets a dog who doesnt like this game at all.
Shoulder mounting, barging etc is another of these play types, and as dogs get older they will be more serious about it and less playful, and certainly iwth my older dog, Rocky, i know its often a trouble sign when he shoulder mounts a dog and has a stiff tail and ears back..... he is waiting for the reaction from the other dog, if its a none threatening reaction then all is fine, but if its a growl and a snap, a fight may occur.
Some dogs your pup will meet will simply exude 'i am boss' and these dogs are very rarely challenged about it, others are more flexible, and soem will never be the boss towards another dog.
But, in human to dog interactions, i firmly believe there is NO dominance. That said, there are dogs who rule their owners with an iron paw, but that is of the owners making and was never the dogs premeditated choice!
I think your dog does sound like she will be a flexible dog, she is just weighing up the situations as they come.
Off lead play is great, so long as you make sure it doesnt go to far, and only you can judge that because you know your dog.
I think you are right to worry that your dog could damage another, all of us need to be aware of that, as really there are very few dogs who COULDNT damage another dog or person.
The way to go about that is to make sure your dog has plenty of access to play with others, and also to make sure she has a 'time out' command, which means she stops playing and comes to you. Teaching her to leave other dogs, and only play when you say so is also of benefit, beyond that, all you can really do is learn your dogs body language and the time it takes between her spotting something to go see and making the decision that she IS going to go over there....... i do this with Rocky because i cant always know if the dog he wants to go see is going to be friendly, hard to explain in words, but there is a point between the ears going 'oooooh!' and him making the choice to go, if i get the command in before he makes his choice, he will come back, if not, he wont.
Watch and learn really!
As far as the tail slightly stiff and the head held high thing, well yes it is a very confident pose, and may have some elements of high status to it, BUT, dogs can be pushed into performing these 'alpha dog' actions when really they dont want to, or cant actually cope with the role.
Rocky is a prime example of that. I used to walk with a couple of ladies and their dogs, two border collie bitches and a neutered male OES.
When rocky joined this 'pack' at first he was only welcomed by the youngest bitch. He was bullied by the OES (charging at him and barking/nipping).... eventually a truce was drawn, and one day rocky just stood hsi ground as dennis hurtled twoards him. After that, whilst not best mates, they tolerated one another, although there were rules (rocky may retrieve dennis's ball from the brambles but he is to give it back immediately!).
Shortly after this, when meeting new dogs, the whole pack would hang back, and rocky would be almost 'sent' out to greet the new dog. If it was a dog that was known to all the pack, even if it was strange to rocky, it would be greeted in a friendly manner, after the initial stiff stance and slightly waggy tail. If it was a strange dog however, it would be bullied, or threatened.
I began to think taht rocky was an aggressive and pushy dog, but OUT of that pack situation and OUT of that particular territory, he never displayed this behaviour at all!!!!
So, one dogs body language can alter dramatically depending on the company he is in at the time, and displaying 'alpha' status at one time does not actually mean that the dog IS an alpha/dominant dog in every situation.
I hope that helps, because now im getting confused!
Em