I don't muzzle Whippy to stop her hurting another dog or person. She never would, even if she did ever make contact rather than just air snapping, which I doubt she ever would, then her mouth is too small to cause any damage to any kind of dog. She's only ever air snapped at another dog twice, when they and their owners didn't heed her warning growl and the other owners were letting their dogs continually harass her.
I muzzled her simply to keep other people away because nothing else was working and it was starting to get me down and making training difficult.
Because she is so small people assume she is 'safe' and don't even attempt to keep their dogs away. This was happening to us on a daily basis, even in on leash only parks people with dogs on extendable leads would let their dog run to the end of it's lead to greet her. It was bordering on ridiculous. Had anyone else told me it was happening I would have thought they were exaggerating, but it honestly was that bad.
With the muzzle 99% of other owners control their dog and give us enough space to work.