Doc is somewhere around 8 or 8 and a half, and he's got it too ... moderate. He's not shaking in the rear end, but he's lost a lot of muscle mass and his tolerance for hard activity has deteriorated a lot ... we haven't changed our daily routines much, I just try to keep the heavy impact stuff to a minimum. He still walks and runs at his own pace, but no more running on the Springer with my bike (something he used to do 2-3 times a week, he suddenly stopped being able to keep up, and I wondered why ... thought it was the heat at first and that we just needed to condition him to Florida, turns out it was more likely pain in his back), no more dragging weights, no more high impact jumping. He still chases the ball but I stop encouraging him to do it when he seems like he's slowing down ... he still likes going for long walks ... he still runs. Big difference is that I just don't push him anymore. No pain meds needed yet, but I could see them eventually being part of his daily regimen if he slows down much more. We do give a high quality fish oil as well as vitamin C supplement and a couple of herbal things our vet believes in as natural anti-inflammatories (a bit of ground yucca root, alfalfa powder, some cat's claw).
Reba had a pretty severe case of it as she aged, we discovered it when she was 9; we found that a good portion of her spine had actually fused by the time she was 10; our old vet suggested that we continue easy exercise but stop all high-impact activity. We did daily walking, 2-3 short walks per day to keep her muscle mass and that dog walked 2-3 times a day, every day, til the day she died ... and would not let me rest if we did not walk. She didn't get really, really bad until she was probably 13 or so ... her last three years she had good days and bad days and she slowed down a lot and started to actually have problems getting up occasionally. We had her on Rimadyl from 9 years old on ... a small dose when she was younger, but as she got older we increased it, and it gave her a huge amount of relief. When she was really older -- 14 or 15, we also gave her a bit of Tramadol here and there if she had a bad day, and that kept her comfortable. We also gave her joint supplements--Fresh Factors and Longevity from Springtime, Inc. and a glucosamine supplement, mostly. Despite the arthritis, I'd say she had a pretty full life, even as an elderly dog ... she still played with Tucker, walked, socialized with the people she liked, ignored the people she didn't, ate with gusto, liked to roll in the grass. I think if we had not chosen to do pain management for her, that wouldn't have been the case, but Rimadyl (and later, Tramadol) had a significant impact on her quality of life.
Dunno if that helps, but that's been our experience with it so far!