Showing aggression towards people during walks

Question
Two months ago I adopted a 2 yr male GSD from our local SPCA.  He lived with a family, kids and was known to be good with dogs and have a good temperament.  They said I could take him home and get him neutered but upon his medical testing he showed positive for heartworm disease.  Before I realized this I was walking him and making him walk close to me, training for simple, sit, paw, lay down and getting him excersize during the walks and learning to walk by me.  He was doing really well but now that he has had his heartworm treatments he had been exercise restricted for most of the time.  He is really great and is wonderful in the house and really bonded to me, but now that I am walking him outside for a short walk he is barking at everyone, male, female etc. to the point that he is lunging, pulling me and I can barely hold on to him.  This is so unexpected b/c when I first got him and walked him he was walking so good that people were walking by and he barely noticed them.  He was and still is leary towards strangers but when I accept them into my home he is fine.  He just does not listen if he sees someone outside and I know I need to get a professional trainer for him but is there anything that I can do in the meantime?  Whenever I talk to my neighbors they pet him and he is leary but then ok b/c I am but he will still bark at them the next time we see them.  It is such an ordeal that I am now even afraid to have him anywhere except for my yard, even there he barks at neighbors he has met, barks everytime.  Thanks.  Irene

Answer
Hi Irene
Back pats for rescuing! I understand why your dog's been exercise restricted, as SOON as your vet ok's this you need to go right back to doing what you were doing. Let your friends and neighbors know for now NOT to pet the dog, but when you stop and chat with them not even to look at him, ignore him completely, you should do the same, put him on sit and leave him there. Remember that dogs pick up very much on your thoughts and attitude, you are unfortunately exacerbating the situation by your fear and reluctance to take him out of the yard. Take him out and walk him, even if you need to use a properly fitted prong or pinch collar. Get him involved in a GOOD obedience class. Not just somebody who knows how to teach sit and stay but a real trainer. Get him some toys that make him thing, the one's you can stuff treats inside. Keep his mind and body busy. IF you can run his little tail off BEFORE you walk him. Play fetch or whatever and then walk him with a pack on. Walk him briskly and calmly at heel paying no attention to him whatsoever, try to ignore other people as much as possible to. Keep head up, shoulders back, I am the queen of the world attitude and he is an extension of your body. For additional information and TONS of help type alpha boot camp into your webbrowser this website is incredible in helping you establish and maintain pack order in your home. And DO keep up the exercise. At least a few times per week
Happy Holidays and you're doing a great job!
Cindi