I hope Prince is feeling better, that is such a helpless feeling when there isn't much you can do for them.
My 11 year old has the problem when she gets excited. It started when she was younger because I took her to obedience class and they had me use a choke collar. Being dumb, I listened. Well...... the vet said that may have brought on the problem earlier than it occuring naturally. I feel guilt every time she coughs.