What a frustrating thing, to do to a dog show with healthy dogs only to bring back what acts like the plague to your kennel. This is what happened to me, I went to our breed Nationals with two dogs in their prime. Both were infected with Canine Influenza, the youngest went down quick. Stopped eating for four days, lethargic, discharge, throwing up/coughing with fever. Four so far have been infected now my matriarch of our kennel is fighting for her life, a senior dog coughing up blood due to some strangers negligence.
Follow protocol and keep dogs home during and some time after, because you are not only risking your own dogs safety. But everyone else who happens to cross your path.