My dogs NEVER wear a collar when inside the house because one time a few years ago Nanook's tags became stuck in the heat register cover. Thank god I was home & the heat was off. But I won't chance that ever again.
I agree, when happy was a pup happy and perky were both kept in the bathroom together when we were not home, well they were playing and happys jaw got stuck in perkys collar, after that collars came off.