Have you thought of Kennel Cough? My pit was walking around the house coughing and gagging for a couple of weeks and before taking her to the vet I figured I would do a search for help and her symptoms were the same as that. This may sound crazy but there were so many suggestions about putting 2 to 3 drops of peroxide in her drinking water and have her drink it. It is not harmful if you just put a very small amount. She immediately stopped the coughing and gagging. I have 4 dogs, 2 that are outside figured she may of got it from there association from other dogs outside. Everytime I filled her water bowl up I would repeat the process and she was fine. Every now and then I do that just to keep her okay along with my boy pit. Hope this helps. Good luck....
