
Kennel cough is like the common cold & has lots of different kinds. Personally I think its pretty much pointless jabbing against it.
You wouldnt know if he came into contact or not with other dogs who have it. When showing we sign a declaration to say we believe our dog not to have a contagious disease (of which KC is one) within the last 21 days. Therefore your dog(or others) can pass it on for this length of time.
Lots of folk(joe public mainly) dont know their dog have KC & carry on walking them regardless, this allows the bugs to be caught by other dogs & so the cycle carries on.