I posted my thread here after my son was attacked by the neighbors German Shepherd...things I've learned:
Know your state laws: in VIRGINIA (and I'm only writing about VIRGINIA) unless the dog is been previously deemed "dangerous", the dog get the benefit of doubt, especially if on it's own property (commonly referred to the "one free bite law")
Know your county code/ordinances: in my county (and I'm writing about my county), I am permitted to use the amount of force *I* deem necessary to protect humans, livestock, and property (i.e. my dog) if a strange dog appears on my property. If I were in a park or bike path, similiar rules apply (I just can't quote them right now).
Carry all of the time: If the dog will bite unprovoked once, he/she will bite again. Unfortunately my neighbors haven't caught on to that yet.