We have a 13 lb. Chi mix (mostly Chi). We have heard about collapsed trachea in small dogs that can occur when you walk your dog on a leash with conventional collar. We had been using a collar, and then recently tried a harness, but our Chi did not do well with the harness. He was chewing at it, and refusing to walk. He even developed a skin irritation from one of the straps - we were fairly sure the harness was sized properly. Is there truly a risk in going back to using the collar, or should we purchase one of the fancy custom harnesses which we have seen on line?