Its worthwhile for any reactive dog to learn to cooperate with putting their muzzle on and then wearing it without discomfort. We recommend a well fitted basket-type muzzle. The right size is big enough for the dog to fully open their mouth (to pant, yawn or drink water) inside the muzzle.
The front end of the muzzle should not be touching the dogs nose.
Some dogs may have an unpleasant association with a muzzle or may be distrustful of novel objects. For a dog who cowers or runs away at the sight of a muzzle, like my lovely trainee Buster, here is a live video showing how you can start your muzzle-training.