Not 100% yet but I think it's a bit of arthritis, a bit of the ol hip displasia, and perhaps even early stages of degenerative myelopathy. She does not seem to be in any pain which would possibly indicate the latter. Shes happy and loves the family and the other pups. Loves eating and her sleep. She's just to the point where time is catching up to her back legs and they are not as strong. She still walks and will run a bit on occasion. We have 2 steps down to the back door and she goes up and down those daily several times. Just some days it's a bit harder. It truly sucks to watch them slow down. So depressing....