My dog has done a little bit of the gagging/coughing thing before but this morning it was really bad. I have to wonder if its the CT. I watched the videos and he sounds more like the reverse sneezing but he also sounds like the second CT video

It almost sounds as if he is choking.
I used to use a collar on him up until he was about 7 months old (I wasn't aware of the need for a harness) but I've used a harness since. He is now 9 months old about 15.5 lbs and a Yorkie/Doxie mix. Do you think it could be the CT? I was just so worried this morning because he has never been this bad. Why all of a sudden is it worse?