Sweep has an old toe injury and does well on Previcox but did not do well on Meloxicam (GI upset within a couple of days). Rimadyl did not seem as effective for her specific issue. All are anti-inflammatories. So it can be a process to find the best fit, and what works for one dog may not for another dog. Unfortunately you can't know until you try, but if you find one that works it can improve their quality of life so much. Sweep is only 7 and I resisted NSAIDs for so long, but no amount of supplements or alternative therapies alleviated her limp; only the meds do the trick. Best of luck to you and Snow.