Get Your Dog Care Questions Answered by Experts
Aside from that, tracheal problems and heart problems can also cause coughing, as can a general virus.
Any time that I hear of an older dog coughing, I immediately think of a heart problem, especially if the dog is not on heartworm prevention.
Parasites CAN cause coughing so you will want to see the vet for a fecal if you have not been recently.
You should be pretty concerned. I think that you should make an appointment with your vet as soon as you are able.
Let me know if you need more details or do not understand.