Hi Paul, I'm so sorry you're going through this with Eric. I hope he feels better soon. I don't have any personal experience with kennel cough, but this is what I found.
Treating and Preventing Kennel Cough
Although most cases of kennel cough will resolve without treatment, medications may speed recovery or minimize symptoms during the course of infection. These include antibiotics that target Bordetella bacteria and cough medicines.
You may also find that keeping your dog in a well-humidified area and using a harness instead of a collar, especially for dogs that strain against a leash, will minimize the coughing.
Most dogs with kennel cough recover completely within three weeks, though it can take up to six weeks in older dogs or those with other medical conditions. Because serious, ongoing kennel cough infection can lead to pneumonia, be sure to follow up with your veterinarian if your dog doesn't improve within the expected amount of time. Also, if your dog at any time has symptoms of rapid breathing, not eating, or listlessness, contact your vet right away, as these could be signs of more serious conditions.
There are three forms of vaccine for kennel cough: one that is injected, one that is delivered as a nasal mist, and one that can be given by mouth. Although these vaccines may help, they do not guarantee protection against kennel cough or infectious tracheobronchitis because it can be caused by so many different kinds of bacteria and viruses. Also, it is important to realize that neither form of the kennel cough vaccination will treat active infections.
The intranasal and oral kennel cough vaccinations are typically given to dogs once a year, but sometimes are recommended every six months for dogs at high risk for kennel cough. These forms of the vaccine tendto provide dogs protection against kennel cough sooner than the injected product.