For healthy hips, the best things to do is to go with adult food, not puppy food, to supplement (I think others probably have a better list of things to give the dog, I think vitamin C is really good for this, but there are other things as well. Usually the glacosomine and chondroiton in dog foods is really not enough. It might be better to go with Nupro or something like that.), keep the dog lean, regular- low impact exercise -- let the puppy be a puppy, run, jump, swim, etc; but do not school the pup over jumps or agility equipment until he is old enough and has had his hips and elbows checked.
All the puppies in the litter may be affected, but it is not necessarily so. It is very possible that only 1 or 2 have the problem. All the things I just suggested will not hurt your puppy. You can x-ray early if you want, 4 months, 8 months, but they will not certify hips until 12 months -- PennHip or 24 months -- OFA. My understanding is OFA used to certify at either 12 or 18 months but they had enough dogs have problems that they did not detect that early, so they changed it to 24 months. Penn Hip checks them differently.
Jenna, RN CGC & Babs, CD RA CGC HIC
Heidi, RA CGC
SG3 Odessa, SchH1, Kkl1, AD
Ninja, RN CGC & Milla, RN CGC
Joy, Star Puppy, RN CGC
Dolly CGC & Bear CGC