Boo will absolutely not tolerate a collar. I've tried a couple of times, and the last time I tried we both decided it wasn't any good for either of us.

Boo nearly choked on his collar trying valiantly to rip the thing off with his teeth. In the process, my arms were torn to shreds but the adrenaline was pumping so hard, I'd felt nothing and thought it was his blood. The whole affair was very messy and violent. I have no interest in getting him used to one as I have heard some horror stories of cats choking to death at home alone as they try to work their collars off.

Because of this, I have not attempted a collar with Bettie. I'm pretty scared of them.