Tomo the diet will have some part but I have seen this so many times with a certain person I know, he breeds a litter of pups and keeps three each time, never exercises them just keeps them locked up and there wrists all end up going backwards. He sells one or two off at about 6 month and after being with new owners getting out plenty they soon rectify. This particular person has still not realised what's happening yet and always wonders why his is no good when older so just breeds again, I have hinted but his ways are the best APPARANTLEY!!!!!!!
Stick with your 27% pal that's fine at that ag