Well, the truth is in my opinion when you have respiratory issues...you need a vet.
They do get sore throats from infection as well as disease. The coughing needs to be determined if it is in the upper airway or chest...the prognosis is different.
The reason I asked about other dogs is kennel cough...is upper respiratory cough that can almost be honking.
We use pediatric cough suppressants to help...but if the cough is due to a lower airway problem the cough syrup can be deadly.
I think you need to get an exam on the dog to atleast determine location and severity of the respiratory problem.
Dr.V
Dr. D.A. Vamvakias
Veterinarian