mine do NOT wear collars indoors. I tried it once with Neko. Luckily my fiance and I were home because he got the round hook that attached his rabies tag to the collar stuck behind his bottom canine teeth. Poor thing was trying so hard to get it off he was bleeding everywhere. We had to make an emergency visit to the vet on a sunday so she could cut it off. We will Never do that again!!! If the cat isn't used to wearing a collar, it's not worth it