Omgosh, This SAME thing happened to 2 of mine last year except neither of them got hurt. Tobie and my Chi/JRT mix, Charlie, were playing. Charlie wears a collar but Tobie doesn't. I was sitting on the couch on my laptop while they played on the floor and suddenly, Tobie started yelping and I noticed they were somehow stuck together. I started freaking out and quickly realized that Tobie's lower jaw was stuck under Charlie's collar. I screamed for my hubby and was able to hold Tobie still while he took Charlie's collar off. Thankfully, no one was hurt... just a little shaken up. I thought this was just a freak accident and I surprised it has happened to someone else