Mark- congrats on the new dog, I hope everything works out for you
Steve- I'm sorry to hear that, I know how you feel though. My dog Bailey was (and still could be if I'm not tuned into her behaviour) very aggressive with other dogs. She's good with my other two dogs but walks were a nightmare. I'll be honest in the fact that I will never feel comfortable taking her to off leash parks due to her aggressive tendencies, she did attack another dog at an off leash park 3 years ago luckily we were able to pull her off of the other dog before she did any damage. However for a moment when it was happening I thought Bailey was going to kill the other dog and thought OMG what have I gotten myself into.
After that I stopped going to off leash parks. I would however take Bailey and my other dog Oreo for walks together. Unfortunately Bailey's aggressiveness towards other dogs started to rub off on Oreo, so I learned to do my best to avoid other dogs while on a walk. Which in a neighborhood like mine were every other house has dogs is near impossible. I got a wake up call when I was walking them and I turned the corner and suddenly there was a husky dog right in front of us, well both of my dogs went crazy and started attacking the other dog, my dogs actually knocked me over and dragged me in order to get to the other dog
I was pretty horrified (and a bit banged up) but really lucky that they didn't hurt the husky and that the husky's owner was able to get her dog away from mine and that she was more worried about me being ok (since my dogs had dragged me a fair way before I regained control) then upset by what happened.
I made a promise to myself that day that I would get control of Bailey and she would not control me. I read a lot of books and watched a lot of Cesar Millan and I started taking Bailey on separate walks. I learned how to get her to heal (walk beside me), I learned to control my fear of her attacking again and I learned to watch for all her signs so I could correct her before any aggression started. It took me a whole year to do all this, but it was worth all the hard work and in the past year I have not had any problems walking her.
Bailey literally went from going completely psycho when ever another dog was within sight to ignoring any other dog we run into on our walks. Yes it was a lot of hard work and yes it was worth it and if Bailey could change I'm sure your dog could to, so don't give up hope yet. The key for me with Bailey was for me to stay clam (not an easy task, but with time I was able to) whenever another dog came into view and to correct her immediately at the first sign of her showing any interest in another dog, to the point were now she pretty much ignores other dogs on our walk. I always keep a close eye on her and there are times when I still need to correct her but in the past year she hasn't even barked at any other dogs we walk by, even if they are barking at her.