I'm really confused and worried because my dog keeps making choking noises. He doesn't seem to actually be choking, but could the gagging sounds be a form of coughing? Are there any other signs I should look for just to make sure it's not serious? Why is this happening?
What kind of dog do you have? If your dog is a short-nosed breed (like an English Bulldog, Pug, Boston Terrier, etc) then this is unfortunately normal. Short-nosed breeds have a harder time breathing and often times will make snorting or choking sounds all throughout their life. However, if your dog isn't one of those, then it is very important to make sure he isn't actually choking on anything. He may have something like a bone stuck in his throat. If your dog will allow you to, try opening his mouth gently and looking inside to see if you can see anything stuck in there. If your dog is snappy or not tolerating you near his mouth, have the vet check. Another possibility is that your dog has allergies. This can also be determined by the vet. We can only give our best guesses as to what may be causing this, but your vet will be able to give you a definite answer.
It might be Roundworm. Our puppy would do this weird choking hacking thing when waking up from sleeping and it turns out that he had Roundworm which had gotten into his lungs. The vet can tell if it is with a poop test (like 70% of dogs get it at some point).