This is Emile, asking all dog owners to please leash their dogs when they're out and about. Even if they're beautifully trained, and drop to sitting at a click of the tongue. Because humans aren't quick enough or clever enough to catch all the subtle doggie signals that pass between two hounds. And humans certainly aren't fast enough to catch hold of giant boerboels that take an instant dislike to miniature schauzers.
Saying "That's so unlike my sweet boerboel/lab/rottie/frankendog" or "The little guy will be fine!" doesn't cut it. Apologising doesn't cut it either.
Leashing your dog when you're drinking in a pub on a busy street would be more helpful. Also when you're walking your dog and chatting on your phone. Or trying to get your dog into your car, while also herding your children and your shopping.
Or any other time your dog isn't securely behind a gate. Just use your imagination.