I tried glucosamine for two years when I first had osteo-arthritis with no effects. My gp just said it seems to work for some and not others. When I was diagnosed with rheumatoid arthritis, my son bought me codliver oil capsules and told me to make sure I did. There was two years' supply there and that made no difference, nor did the turmeric tablets I tried. My GSD x Lab, aged 13, is having problems now. Glucosamine didn't work for her either and my vet prescribed Carprodyl which does help and she can run around quite well. Our 12 year old Lab is also on them for OA but a higher dose. The vet said one of his hip joints is crumbling so he's not allowed to go for walks now, although he seems much better on the meds.