
My puppy sales agreement says the following:
"Every effort has been made to ensure that your puppy is healthy in body and mind, and is sold subject to it being understood that as a living creature it is impossible to predict how it will continue to develop, especially as regards behaviour over which you will have the principal influence.
Both your puppy's parents have been HIP SCORED with good results; hold a current EYE TEST, and NORMAL KIDNEY blood test. They are typical examples of the breed, with excellent temperaments.
.................
It is essential that you take your puppy to a Veterinarian in the first few days for a health check, and to make arrangements for inoculations. Should there be a health problem not attributable to its journey home (travel sickness) or change in food or water (tummy upset), and this renders him/her unfit for sale as a companion, a full refund of the purchase price will be made on production of a Veterinary report."
I am pretty sure the KC says nothing about guarantees, as of course a puppy sold changes dramatically week by week, and is a living being. I don't see how you can guarantee anything other than it being healthy at the time of purchase and parental health clearances. I would imagine selling an adult dog would be more predictable.