You can pet this dog. In fact, she'd love it if you did.
People see a dog wearing a muzzle and cross the street. But most muzzled dog are just normal dogs, who've done some normal dog-like behavior. For example, maybe she got in a dogfight, or barked at a child, or almost killed a kitty.
And unlike most of us, this dog-handler is being responsible, and re-socializing her dog safely. Muzzled dogs learn how to make new friends and keep the old!
Some dogs have a more difficult time than others while learning to make friends, for example, on a walk. A well-fitted basket muzzle means biting is no longer an option. Even threatening to bite is useless. A muzzle properly used can really teach and not just manage behavior. A muzzled dog can now learn to make friends rather than enemies!
Classic children and dog movies, like 1001 Dalmatians, and Lady and the Tramp, portray the muzzle as a cruel device, like handcuffs. But properly trained, any dog loves her muzzle. It's more like a piece of jewelry, a wearable party dish. Dogs love the leash, right? The muzzle can also be good news that a walk, socializing and treats are about to begin. One side effect of good muzzle training is that you co-currently train a stronger recall, and you get a new cue for it too. You know you've done it right when you hold up the muzzle, and the dog comes running!
To keep that strongly positive response, we have to practice reinforcing the muzzle on a regular basis. Have the dog wear it whenever she goes out partying for at least a couple of years, and she will associate the muzzle with good times. For more details see www.wholedogcamp.com . 
A dog wearing a properly fitted wire basket muzzle can bark, eat, drink, and play. The only thing s/he can't do in this outfit is retrieve, nor bite! (This dog however can manage to grip and play with a toy rag in the play yard, and she also likes to push a ball around with her nose).
A muzzled dog is extremely vulnerable if attacked, and so handlers must provide muzzled dogs with a safe, protected environment. Only friendly, harmless dogs and people, or other muzzled dogs, should interact with a muzzled dog.
The muzzle offers a much better chance for success with dogs that might make mistakes. The muzzle protects and helps strengthen the bond between the handler and his dog, by allowing for positive error-free learning. It de-escalates tension between a nervous dog and handler by putting the handler clearly in charge. The muzzle takes the guesswork out of safety while socializing.
