Hi all, If anyone can help or offer advice, please do, I will take any help at the moment. I have had dogs my whole life, including GSDs, but had them all from pups and they've all been beautifully behaved. Just over a week ago I rescued an 8 year old GSD. He is lovely with all people. He's learnt the basics; sit, wait, come, paw, watch, heel etc. But he had never met another dog before I got him so had been majorly undersocialised. And as I've never had a rescue before, I've never had to deal with this. He is so reactive to any other dog. Whether they're off the lead or not. He barks, pulls, hackles up. Even if they're in the distance and he just spots them. He is a big dog and has nearly pulled me over once. I've tried various people's approaches like Caesar Milan, Shaun Ellis and a few others and just nothing seems to work. I try to be really calm and if we see another dog not tighten the lead and just keep walking and not react to him reacting, I've tried telling him off but this works him up more, I've tried when we see a dog in the distance giving him a treat or tennis ball to associate something positive with dogs and this actually makes him worse. But I just don't know what method to try now. He is better if we walk in circles, his hackles are still up but he doesn't bark as much as he's still moving, whereas if we're stationary and at a narrow place he gets a lot more aggressive. Difficult to say if it's aggression, anxiety or undersocialisation or a combo. He has also attached very strongly to me and potentially he is being overprotective of me. It's embarrassing because people look at me like I've just raised a dog really badly and it's frustrating because I don't know what else to do and we have to keep making U-turns in our walks to avoid others. I haven't tried him off the lead because I'm not sure if hed come back if he saw another dog so I can't say how he would be off the lead. I want him to be able to enjoy walks, relax and maybe just ignore other dogs if not be happy around them. I want to give him the best rest of his life I can as his past hasn't been great, he deserves that but I'm unsure of where to go from here. He's walked between an hour and 2 hours a day and we do training to mentally stimulate him. Thank you in advance!