Over time, I've had two of my charges (not associated) come down with this while still puppies. Both had their full series of puppy shots. On was treated with antibiotics/rest, the other with herbal teas/rest. Both went to Vets that were non=holiostic. What types of txs. have you come across?
I believe kennel cough requires antibiotics to cure it. Kennel cough is interesting as it is like the common cold and an airborne virus. It could be spread from dog to dog or from communal water dishes or toys. When I worked at a doggie daycare, if a dog had kennel cough we would immediately clean and disinfect water dishes and dog toys. I would also go home and wash my clothes and take a shower immediately too as it is airborne. the vaccination bordetella is a great non-core vaccine to assist in preventing a dog from getting it as well.