》hearty slap on the muzzle

I think you may have very very nasty suprise in western country. Dogs there NEVER wear muzzle. Plus touching a dog, who has not bitten you yet, is a crime there.

》If the dog bites, it will probably only bite very briefly and then let go again. Holding and shaking people like prey is unlikely if it hasn't been conditioned. I don't know what you can do in this case

Pitbulls have reflex to bite, and hold no matter of what. They were bread to kill bulls this way! Pit will not let go, even when stabbed with a knife!

Owners should carry "break stick", it gets stuffed into mouth to force it open (break the grip). 60% of deaths from dogs in west are because of this reflex! We have no rabies, we have pits!