I can't give details because it's my friend's dog and was over 20 years ago, but...
Her Standard Poodle at an early Vet check when he was around 3 months old was pronounced by her Vet to have the worst early age HD he'd ever seen. He advised her to return the puppy right away as per her health guarantee. She knew if she did the puppy would be euthanized and besides she was in love with him so they decided to manage as best they could and take things as they came.
He got better. Her Vet, mine too, said HD was not well understood at the time but some research showed some improvement in cases that were bad at a young age. The dog could never go hiking or cross country skiing with her, and me and me dog, and that was the plan when she first got him. But he was able to live to old age, 12, and relatively pain free with meds and careful exercise. I do not know if this is still thought to be the case but that's what she told me.
I should note, this was long enough ago that health guarantees that replaced the puppy were fairly common, and that was the only option. Nowadays a health guarantee would replace, reimburse the purchase price or pay for some health costs with proof of diagnosis from a dog professional in whatever was the area of concern; eyes, hips, heart, temperament, what have you.
What does your health guarantee say?