My dog doesn't even have a "collar". I believe when we adopted her, she came with one... but lordy, that's far too small now. We use a harness on her instead. It helps her back when she's walking on a leash, and the vet recommended it with our past dog when she had back surgery. We didn't even want to go down that road with Daisy, so it's a harness instead. We don't even have an ID tag on her either.. now I'm feeling like a bad dog owner. We don't have a fenced backyard, so when she's outside with my dad, she uses a leash. And when she's out with me, she follows my commands so I don't need a leash for her. I carry one incase, but I'm training her for certain things and trying to clean up her act a bit... her "piggish" act. And oh yes, her harness is always on her unless she's in the bathtub.