over friendly shepherd

Question
Hi, i have socialized my white female german shepherd very well since 12 weeks old. She is now 17 months. We walk alone & in packs with other dogs & owners daily for between 2.5 & 4 hrs in 2 sessions {we have sit breaks during this time for coffee etc} This can be canal/field walks off leash, or built up areas such as towns on leash.I have always encouraged her to greet dogs & people to ensure a friendly animal. However because of my need for her to be friendly she feels she can greet every dog every time. I'm afraid i've always allowed this with the owners permission. Now she is older & has plenty of dog friends & activity i dont want her greeting every dog we pass. I understand i've essentially trained her to do just that, but when i tug the lead to stop her greeting she has started to rear up like a horse & protest. I am using squeaky toys to divert her attention {which i successfully used to stop her herding everything that moved}. This works sometimes but feel i may have made a mistake in my training with her now. I must also confess that because of this rearing up i have on occasions then allowed her to greet anyway { sorry} and then she "lunges" forward excitedly. I am home all day & her basic sit down stay come training is good and she loves to do small tasks like find/fetch things for me but she has become 50/50 whether she will respond to these basic skills outside when greeting other dogs { or people }. She doesnt growl or bark at dogs and never has and will walk away from aggressive dogs but she will jump up me challengingly if a strange dog passes now that i have not allowed her to greet and nip my ankles when walking on.I feel i've let her down as its only my training thats provoked this. This started about 4 weeks ago and i would like to nip it in the bud asap and i seem to be failing miserably. I have tried the shaking a bottle of stones & shooting her with water but as she swims alot & plays with the hose at home it only stops her for a second & she will still jump me afterwards.I have ordered a canny collar in hope. I did a lot of research before purchasing her & now feel its going to pieces. She is due to be neutered next month. I love her to pieces, she is a great companion & i want her to enjoy life to the full but fear this challenging behavior may prevent some of that. I am female & 48 years. I have so far trained her with a quiet but firm voice. I have never shouted or "smacked her for failings & worked with the ignore negative behaviour & reward positive and she has previously responded well to this. Do i just need to persevere or have i created a real problem. Thanks in advance. Carol

Answer
Much of what you have done is right and no, you don't want to start smacking her.  You do need to be firmer with her and showing her you are in charge.  The key to most behavior problems is approaching things using the dog's natural instincts. Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog. Life is much easier if the 2 legged pack members outrank the 4 legged ones. You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at http://www.dogsbestfriend.com/ For more on being top dog, see http://www.dogbreedinfo.com./topdogrules.htm

Neutering her will be a big step forwards too.  It may take a month or 2 before you see much difference from it.  

I don't know exactly what the canny collar is.  It seems to be another style of head collar similar to the Gentle Leader.  They are designed to prevent pulling.  I did find a gentle leader was effective with our last puppy when it came to lunging at everybody or dogs we met.  It could help too.  

while the neutering and collar will help, you will need to do the going through the door first etc. stuff too to claim your place.