Here are some tips to help understand what is really going on for your dog, and how to adjust your dog's social agenda to be more aligned to yours.
Managing the greetings for your pup at a young age can help set a precedent for later in life. I had a social butterfly for a dog when I first got him - At the tender age of 3 months old, he ( Basil ) grew up on a film set with lots of people and lots of dogs at his beck and call for 2 months. This started his own ideas about who he gets to interact with and when. At 6 months of age after the film was complete - I had to deal with the after shock of what the last 2 months brought on. A dog who pulled on leash to say hello to anything and everything that he thought worthy. I was just a puppet on a leash! I knew I had to shift this quickly... but how and why?
What a social butterfly dog looks like: A dog that sees a dog or a person and absolutely positively has to say hello to them. Greeting another dog and person requires certain etiquette - a polite greeting is one without too much stress or excitement. This left unchecked may evolve into barking or pulling on leash to visit with the object in their sites. Not fun, who wants one arm longer than the other.
Why is it a concern?
When a very excited dog says hello to another dog, there may some jumping around, sniffing of the face, eyes and ears ( which is literally a "in your face" greeting ) and be pulling on the leash while doing all of the above. Pulling on the leash creates a 'bug' eyed kind of look in the dog pulling and also can manifest a crab like scampering towards the object of their choosing. To the dog being approached, this can and will be interpreted as a stressed animal approaching, which in turn will place the object of desire on guard. This stressed or excited greeting may go sour quickly if the excited dog is allowed to get what they want in this state of mind. After one greeting has been rewarded in this state of mind - the next greeting your dog will think they need to get to level 8 ( out of 10 ) to say hello - so thats the excitement level they will get into for the greeting to take place. If left unchecked - the level of excitement or stress can reach 9 or 10 - at this level fights can break out - because not everyone wants to party all the time. Even Lindsay Lohan can attest to that!
A more appropriate greeting is a calmer bum sniffing and circling around so the latter is available to all. Then the play may commence once they have figured out who they are interacting with.
What dogs sniff and why? Dogs sniff each other to see who they are and how they are feeling, if they are in season ( available mating material - if only it was that easy for people! ) and if they are healthy or under the weather.
How to alter this state of butterflyitis... Firstly, avoid rewarding the state of mind of the dog - on a scale of 1-10 the greeting ideally is between 3-5. Calmer greetings are going to help you control the situation better, this may require a short intervention before the next time your dog says hi to another dog, or person. Having your dog sit and then given permission with a "OK - go say hi" from you - is a step in the right direction. If your dog is unable to sit with the excited state of mind - walk them away with a little more distance and try again. When your dog learns that their calmer state of mind is being rewarded - the party animal in them will become more quiet. Keep in mind - this may take attempts in various situations for your d learn that calmer greetings are approriate too!