> I signed a contract stating the puppy had been checked at a vet prior to purchase and no issues were identified.
This is strange to me. If the vet had checked it as the breeder said and they knew about the issue then the contract should not state that no issues were identified as this is not true. Either the breeder has lied about it being vet checked or lied in the contract about what was found.
Yes an umbilical hernia can resolve its self. Many vets unless it's server will wait until the dog is neutered to fix it if it's still there. So it is entity possible it could revolve.
I've also heard of one vet saying it should resolve waite and see to a breeder and then another vet with the new owner saying no it needed doing. Although I can't imagine a vet would say a hernia would definitely resolve its self rather than only stating it might do or that it would likely resolve its self.
Do you live near the breeders? If you do I'd take it for a second option to the vet the breeder claimed did the vet check. If not I would get a second option either way
> I will get a second opinion but if the opinion is the same is the breeder legally obliged to do anything etc.
You would likely be within your rights to return the puppy for a full refund.
You could try requesting the breeder pays for the op if the hernia doesn't not resolve by 4 months old and sign a new contract stating this but i don't think you could force this if they refuse and offer a return instead. Citizen advice offer free leagle advice.
If I was the breeder I would have told you about the hernia, had it in the contract that if it had not resolved by a certain age that I would refund the cost of the repair.