When my Shelties was 4 months old he jumped off the front porch and broke is his back leg. He was is a cast for 2 months. About 2 years later he stared limping occasionally on the leg. I took him to the vet and he said that he had arthritis due to the injury. He started him on Glycoflex (glucosamine and shark cartilige) everyday. He also gave him Rymadil but told us to use only when he reall needed it. I think since he was started on the Glycoflex he has had maybe 2 Rymadil. The Glycoflex has worked really well for us.