
I know how you feel, my walks with Zak (GSD dog, 3 years old & neutured) & Tilly (Terrier x spayed) can be quite hair-raising. I only have the problem on the their home territory though. At shows the GSD now walks quietly past dogs which even have a go at him. I am sure 2 dogs (whatever sex/entire or not) give one another confidence to defend one another & challenge others. I live on a road where there are a number of dogs left in gardens to terrorize anyone trying to get past with their dogs. I know someone who's dogs actually fight between themselves as they go past these gates, because the barking winds them up. My dogs can also recognise these dogs when they are on walks, the 2 of them will not tolerate dogs which bark at them.
I also have to put up with an alcoholic neighbour next door who lets his pointer bark for hours on end in the garden. My boy now thinks he has to protect me from her all the time. They will never, ever be friends. Zak grew up, never seeing her over the wall, but always listening to her bark.
The owner occasionally when really drunk (most of the time) lets her out of a taxi at the top of his drive. She flies over my front garden & throws herself at my gate barking. You can imagine what it's like. I don't blame my dog for trying to defend his home & me from her. The gate actually bounced open the other week & my dog pinned her down on my front garden. He didn't bite her, she was ok, he came straight away when I shouted him. The idiot of the owner still does it though! It is bliss when he is away from home.
Please don't anyone suggest moving, my home is my castle! I lived there before he did!