OKRAD, buddy, friend, sister,
You did the right thing. I cannot STAND owners, particularly of small dogs, who allow aggression to go unchecked! I say especially small dogs because it's like it's okay as long as they're under thirty pounds, but it isn't. I made the mistake of taking my dog's food dish away from my sister's yorkshire terrier and the little sh*t tried to attack my hand. Before I could throw it at a wall Annie attacked her and pinned her down for me. I went on to have an infuriated lecture with my sister (14 years older than I!) about how her dog's behavior was totally unacceptable and I couldn't believe she wants a baby when her yorkie is such a vicious brat. After spending several days with her and she saw my dog's behavior and how her yorkie's behavior was totally reformed toward me thanks to little Annie's no BS policy, she agreed that it was CRITICAL to get her dog trained. NO dog should be allowed to bite others, and if it had been a kid out there and I saw that shit happen, I would have probably beat the hell out of it myself.
But nevermind other dogs, when my dog is in the other room I have complete control over her an awareness of her actions. If she is even slightly out of line, my housemates barely get out the A in her name before I snap my fingers and she comes running in with her head down. If I ever saw her bite someone, she would be in such a WORLD of hurt. Thankfully, the way she's trained now she would have gone after a little mongrel like the dog who attacked you and taught it a lesson herself.
Dogs are supposed to be pets that are loyal to humans. They have no other purpose. They were bred to serve us and that is their place. You did the right thing, and I hope that that dog is taken home by someone who cares enough about its LIFE to train it properly. As it stands now, its behavior could have gotten it put down. You may have saved that dog's life by having her taken away from irresponsible owners.
I could go on for pages about how that dog could have suffered so much worse a fate if it had attacked someone or something else, but I won't. All I can say is that I love dogs, but I saw a German shepherd lock onto my SO's arm like an attack dog once, and he had about two seconds before I was about to slit that beast's throat. Owner pulled him off. A*sholes.