I have a retired racing greyhound with decent prey drive. I don't know much about fearfully reactive dogs to be honest. I took him to the groomers today because I knew there would be lots of small floofy dogs and owners letting their dogs run around on flexi leashes while they paid at the counter. I didn't receive a single negative comment. He wears it to places I know there will be cats or unleashed/unattended small dogs.

I've only used it at the park a few times, but only at a specific park where I knew all of the dogs and owners. The only addition was a few beagles he chased a little too enthusiastically. I muzzled him and once he determined that the beagles weren't rabbits I took it off. I want to stress that I knew that all of the other dogs had played well with my dog for months and the owners pay attention. Throwing a muzzled dog into a park full of poorly behaved and/or unfamiliar dogs can end terribly.

I overheard one woman making a comment about the muzzle (didn't hear exactly what it was) and another woman explaining to her that he could still pant and drink water and was probably wearing it because of the relatively small dogs on the big dog side. We also have a few greyhounds at this park that are sometimes muzzled for similar issues so I think some people might think it's a greyhound thing.

If someone asks about the muzzle I just say "I don't trust him 100% with small dogs" or explain that he was bred and trained to chase small fluffy things that move fast and that I would rather be 100% safe. I've never gotten a bad reaction to that answer.

Again, this is prey drive and not reactivity, which I understand are different issues, but good luck and thank you for being a responsible owner. Even if your dog isn't a dog park dog muzzle training is so useful and provides peace of mind.