This isn't quite correct - providing the terms of the contract are made clear at the outset and the bitch owner accepts those terms prior to any mating and falls into the same arena as any other agreement made which could be constituted as a contract (i.e. offer and acceptance)

When you enter into a contract, by buying a product or using a service - you agree to the terms of that contract, which may, or may not include endorsing any resulting pups.

Whether it would stand up in legal terms would depend on whether the terms of the contract were deemed 'unreasonable' in a court of law.

Unless there has been a test case on this, then no precedent exists and basically - until it has been tested in a court of law, and a precedent set, none of us know which way it could go.

I suspect under the terms of the KC, if you have witnessed and signed the stud documentation to say your dog has covered their bitch - you couldn't add a clause retrospectively as that would be changing the terms of the contract - making any original agreement null and void.

The only way you would know for definite that all pups had been endorsed is if you see the paperwork for the whole litter - which would only be available after the KC have registered the litter and despatched the paperwork.

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In theory - both breeders selling pups and stud dogs covering bitches can be sold / used under whatever terms the breeder / owner requires - and contrary to popular belief - under the law of offer and acceptance of contract, they are as legally binding as buying a fridge from Comet or a cake from M&S.

I know of the odd breeder who charges high fees for endorsements to be lifted (once the health conditions have been met) - legally (until someone is prepared to challenge it in the courts) - they are doing nothing wrong providing the terms are made clear at the time of purchase (morally of course is another issue )

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What you need to know before buying a Labrador puppy