I asked the same question a while back. I think it depends on the cat, and how they live. Allen wears a collar and has never ever had a problem. Pouncer is a great escape artist. He doesn't wear a collar. I put a harness on him when we go outside. the quick release colars are great. If the cat gets caught on something, all they have to do is tug (which is a natural isntinct) and the collar releases (hence the name )