GSD/agression towards other dogs

Question
You have been so helpful to me.  I thank you.  As you have suggested, I am not taking my GSD to the dog park anymore. Today I walked her and she met another dog and immediately started barking and growling.  I corrected her each time and she settled as I commanded her into the "down" position.  She eventually greeted "Sandy", and they sniffed butts, but then she would bark and growl again and was immediately corrected.  She again settled and they sniffed each other again. She did not attempt to attack the other dog and her hackles stayed down, and her tail wagged. I feel like progress was made today and no bark collar was used.  O feel that continued exposure to other dogs like this will help her learn to behave.  What do you think?

Answer
Sure, at some point you have to use other dogs while you train a dog who is dog-aggressive. It is good to have short interactions always on-leash, like you mentioned.  Not every other dog is going to be good for this, so just make sure the other dog is safe and will not challenge her.  When you are walking down the street, practice having the dog heel and completely ignore other dogs.  This will also let her know that she won't be able to greet every dog she sees, and should be focusing on you.  If she is heeling, you can immediately correct her for any looking at other dogs.  If you have a trainer who has a "safe" dog they use for this, you can also do exercises like having her do a down-stay right next to another dog.