Furosemide pulls fluid out of the body, and if there is a lot of fluid in the lungs as a result of mild heart failure, the dog coughs
. Furosemide pulls the fluid out of the lungs, and the cough usually improves.
If he has a good quality life, keep him in the best condition he can be. When you go to the vet next, ask if the vet suspects a heart or lung problem, and from there, you can decide what treatment is best.