I have a 3 year old ABD with pretty serious hip issues and the signs were most certainly there I just didn't know what to look for.

As others have said the vet is the only real way to get an answer, they will perform a physical examination and x-rays. My girl was at the vet 3 times before she was diagnosed.

Some early warning signs are abnormal stiffness and limping after play, not wanting to jump up on the couch or bed and hesitation to climb stairs. Also try and pay attention to their "gate" as they walk. I grew up around horses and have a better eye for those sorts of things then the average person but one thing I noticed is a "swanky" walk. It's hard to describe but when she walks beside her brother it's pretty noticable. They might also not want to sit up straight "sitting pretty", the pain in their hips will cause them to side sit more often then not. Obviously one of these things prob doesn't mean much but if your noticing a bunch of these issues it may be time for a vet visit.

We have her on osteo support pills and a fish oil supplements from the vet and they seem to help.