Sometimes muzzles are needed for the pet's well being, especially if they need to have a medical procedure or treatment done. When I rescued one of my dogs his ears were so badly infected he wouldn't let me treat them without a muzzle...until overtime he learned that I was helping him, not harming him. Then he was fine without the muzzle. The vet techs still can't touch his ears because he doesn't trust them like he does me but I never could have earned that trust without the muzzle. Same thing goes for dogs needing nail trims or other grooming - they may be fine with you but if a stranger does it often times dogs bite out of fear. A muzzle protects the groomer as well as the dog.