Unless Kodee had been totally quarantined from all dogs in the previous two weeks or so, she could easily have picked up kennel cough anywhere if not vaccinated (the incubation phase is at least two days but up to two weeks). If anything, vets tend to use disinfectant generally anyway so most vets, even with sick animals going in and out, are going to be healthier environments than say, boarding with someone who boards dogs that are in and out, and doesn't require kennel cough vaccines (mine picked up mild KC twice in that sort of environment; so I vaccinate now as the vast majority of KC cases are caused by the ones in the vaccines. Recently when I had boarded my dogs in a place that did not require the vaccine at that time, KC came in with an apparently healthy dog that developed symptoms by that evening, swept through and affected *every single dog* except my three -- who were vaccinated. Which alone kept the dogs comfortable and healthy, and saved me about €200 in vet charges and medications). I often bring one or the other of my dogs along when I have rescues in to be checked by vets -- so we are talking very regular visits to the vet over a couple of years now, usually without KC vax at the time -- and I've never had a single illness arise out of those visits or had a rescue get ill from the vets, but I have from home boarding. So vet exposure is always possible, but this is a very comnmon virus that could be picked up anywhere, even from your own clothes after petting a healthy dog in a park that might have been exposed to the virus and have it on its coat.
KC is highly contagious and IS airborne so can stay out in the environment. Any contact with any infected dog or in its vicinity risks infection for a dog, but so does contact with clothes, cats, guinea pigs, bedding, groomer's waiting rooms and equipment... all can carry KC... and a dog can remain contagious for a couple of weeks AFTER it seems to have recovered! And note that it is felt that many to most dogs get KC as a result of ALREADY having some other minor virus(es) that have already weakened the dog's immune system and made it susceptible to KC -- they don't generally just get exposed to KC and then get KC (just as we don't get colds from exposure to every person with a cold). The reason dogs in kennel situations often get it is that the multi-dog environement and stress makes them more succeptible. A brief trip to the vets would be a lot less likely to cause an infection than many other day to day environments *if* the dog is susceptible.
Most dogs that get KC will have it work through pretty easily on its own or with some mild medication to relieve symptoms (as with colds, there is nothing that 'cures' it) but I have seen many really ill dogs from it, coming primarily from pounds/shelters/boarding kennels where it will sweep through a whole kennel -- and while most dogs manage it well there are always a couple, especially puppies, that get really, really sick. Puppies are at higher risk of it developing into pneumonia. Puppies are particularly susceptible -- just as children are - to illness -- because their immune systems are untested and relatively unformed. NB: some breeders such as Laura Lang (Roycroft) believe it is *good* for puppies and for dogs to get out and about, incuding to vets, precisely to help build up their immune systems. If puppies are not exposed to the real world, there's a good argument that their immune systems ultimately are less robust and less able to handle any kind of assault on it. She takes puppies out regularly and says she has never had any problem in doing this).
This is a useful list perhaps of things that will weaken a dog's ability to fight off kennel cough itself (because these things affect the thickness of the mucus in the dog's throat/nasal passages that defend against infection):
shipping stress
crowding stress
heavy dust exposure
cigarette smoke exposure
infectious agents (viruses such as reovirus, adenovirus, parainfluenza virus, and even the distemper virus can be initiating infections)
Cold temperature
Poor ventilation
My guys have only picked up KC twice and both times, when unvaccinated at the time, and it was little more than a mild cold in symptoms and it went away on its own in about a week. Most of the time it will be more a hassle than a serious problem so that might influence whether people vaccinate (if it isn't required).