So sorry about your dog, but you have done the right thing. This post has resonated with me
I am sitting with my corgi x who has a heart murmur and has been coughing for five minutes. He is on Vetmedin. He is otherwise quite lively. This is the third time its happened.
I never realised that what he was doing was coughing as it always seemed as if he had something stuck in his throat. I am fearful now for his future. Got enough going on in my life without losing my dog.