My two always wear a collar, with an id tag. But, that is because they go outside sometime. They are not microchipped (probably should have that done), so I just feel better that someone will have my phone number if they are found. So far, so good. Mimi is 13 years old and she really doesn't stray far from home at all. And Butter seems to be much better at staying close to home these days too. But he loses his collars frequently, so I am constantly replacing them!!!