Question for breeders - mastiff puppy with hip displasia despite guarantee?

Hi. I run a mastiff group in my area with almost 60 members now. One of our members with a beautiful 5 month old English Mastiff puppy named Solomon was just diagnosed today with mild to moderate hip displasia. He was bought from a breeder in CA and was from champion lines with a 2 yr health guarantee. How should these owners react to this vis a vis the breeder and what should they do to support their pup? How does this happen? And how often does it happen with reputable breeders? I have a feeling my group will now panic a bit about their own pups and I have had a pang for my own. I realize hip problems go with the breed but when you pay for champion lines and research for a great breeder paying for health guarantees, it just seems tragic. Any suggestions as to how to help the owners, my group, deal with the breeder or medical options for Solomon are welcome. Is an operation for his hips worthwhile in this situation?