Thank you Karen for that information. Keep in mind that dogs are just like people in the sense that they are all born with a personality. Most dogs react to other dogs out of fear more so than because they are an alpha type dog. Fear based reactions are harder to work through, take the longest and sometimes cannot be changed. Sometimes as humans we do reinforce that behavior depending on how we handled it in the beginning when we first saw it.
What you want to do is daily training to get the dog to focus solely on you and when you see that a reaction may be coming you want to give the command leave it, then give another command of what you want the dog to do, such as heel or sit. Daily positive training can help to boost a dog's confidence if they are of a fearful and can show you as the one in charge if they are an alpha type personality.
I would do clicker training with the dog where the right behavior is marked and there is a reward for the right behavior .
I would also do behavior adjustment training which is done slowly and also works on desired behavior to help the dog over this.
All of this will take time, it is not an overnight fix and can take 6 months to a year before you start to see a change and training is ongoing for life, it should never end even when you see the dog is making progress or dogs backslide and revert to old behavior.
Clicker training/positive method training/ print off
video’s to see how clicker training is done, scroll down to videos http://www.clickertrainusa.com/clicker-training-videos.htm
clicker maintaining focus http://www.clickertraining.com/files/auto-eye-contact.pdf
Training method BAT http://empoweredanimals.com/