What should I do if my old dog has started coughing/wheezing?

He is 13 years old and has recently just started coughing. I have looked online and it says that it might be symptoms of congestive heart failure. I was wondering if anyone knows what type of medicine I should give him or what I should do?

You should definitely take him to the vet. Your dog is a senior and his health can start to deteriorate at this age. But, he needs to be examined by a vet and diagnosed. Only then will you know for CERTAIN what he is ailing from, and the vet can prescribe the appropriate medication.However, it is possible that he is suffering from allergies or even Kennel Cough. So get him to the vet before his condition worsens.