In better neighborhoods, it is still a good idea to carry pepper spray at a minimum. In practice, I have seen a little “toot up the snoot” get a pit bull’s attention enough for him to release, where a gun would have been impractical.
Importantly, in a dog on dog confrontation, when people try to pull them apart they often get bit. Even if they don’t, they can’t usually separate them. When using pepper spray, you can both get safely close and give out the warning “pepper spray in 3...2...1!”, like “fire in the hole!”, as fair warning for the people involved.
The rules are very different for a dog on person attack. Spray first and ask questions later, because every moment is another chance for a grievous permanent injury.
As frightening as it sounds, if the first pepper spray doesn’t work in such a case, go for a heart stab with a knife.
I haven'y had a need to try it but I understand that a 50-50 solution of ammonia and water in a Windex-type of spray bottle will do the trick as well.