I got in some legal trouble before so I can't get guns, concealed carry, which also happens to be only allowed circumstance for tasers.
Where I live, open carry of non switchblade knives is allowed. I think this would be more effective than pepper spray in a truly dangerous loose pitbull, Rottweiler situation. This is the option I was thinking about. It is just for the extreme rare circumstance, which might mean death and serious injury for me and my dog unless we were prepared.
For what it's worth, I've gone out many times unarmed with the pooch, I stay away from dangerous areas and situations, I've talked, shouted, avoided and ran out of slightly dangerous off leash situations with my dog versus other dogs (I always keep my dog leashed). Worst thing was a few years ago, some old thug had his rottweiler without a leash. It chased me and my dog. I was in pretty good shape at the time so we just ran away and it left us alone. But I hear stories.