
Your original post does not appear to say that she knew about the coughing! It appears that she discovered it later and that is why she rang you.
I have a freind who is in same position, a litter of 10 pups just ready to go to all their new homes and they have got KC. She has not been to any shows since bitch whelped,avoided all doggy get togethers, and yet they have it.
They are right as rain in themselves, eating weell and plaing, and in fact one has gone to it's new home, where there are no other dogs, as the owners were happy to do so, but the other 9 foir various reasons will now have to stay put.
It is exactly7 the same as bringing a cold home to your relatives, the infection often occurs before symptoms are evident.
I would minimise contact between the pup and the mother of the litter and herpups, and pray, as things will run their natural course.
On a brighter note I have known pups of this age and older get over KC cough with little trouble,though again it can be fatal in some very young pups, a lot depends on the Dams immunity.