Hi erykah! My dog Connor is on Sasha's Blend now, as well as Cosequin - as combination glucosamine and chondroitin supplement. He's been on them both for roughly two years.
He's a small dog & is only four, but due to a problem with his leg bone, he's at risk for arthritis. He was limping really badly for a while, so the vet recommended him going on those two supplements. We've noticed a huge improvement. He never limps anymore, unless he really runs crazy outdoors for an extended period of time, and doesn't seem to be in any discomfort like before.
I'm not sure how it would work on an older dog, but I know they have been great for us. Maybe you could think about doing a combination of the two supplements? I know the glucosamine is highly recommended for joint issues.
"Happiness is a warm puppy."