@Paivi:
Thank you for your suggestions!
I am afraid Rairai would not tolerate a nebulizer, she is not the most cooperative dog I have met. But you never know before you try.
Rairai already suffered from the cough before she started this medication for heart problems. So probably they are not the cause.
I'll meet a homeopath next week, she lives in Germany and works as specialist on homeopathic treatment of animals. I hope she can help.
I think that is a great idea…. many homeopathic treatments really help our elder kids... my Kistii will be 15 in December