My yellow lab Andy is eleven. He has had kennel cough for three months. After the first month, I took him to the vet who has seen him since he was a puppy. After expensive testing and two treatments, the cough still exists. Our vet mentioned if the cough remains, other testing could be done. He also threw in the fact he was getting old. Andy has always been in good shape. Any encouraging thoughts for myself and my best friend?