I'm glad both of you didn't get hurt. I've had similar experience but not as severe. I didn't report them. The owners are really nice people and do have a leash/handle on him. It was the relative/pet sitter that didn't have him on leash.
Anyway, funny enough, Buddy (the dog that attacked) is friends with Magnus now. Magnus even sits in front of his house when we walk by to see if Buddy would come out and play.
There are few dogs (labs mostly) that's not leashed. But I don't have a problem with them because I know them... They mostly just come up to me for treats. (I always bring extra treats for other dogs to get friendly with them) If there's a dog/house I know that's not really friendly, I just avoid walking that part of the neighborhood.
Btw... This was something I looked into when the first attacked happened. I ended up not getting it b/c I just started walking when I knew hardly anyone was out. Thought maybe you'd be interested.
Amazon.com: Petsafe Sprayshield Animal Deterrent...