Oreo recently ruptured her cruciate ligament. (You can see the thread in Dog Health about it.) At our first vet visit, the vet suspected the injury, but couldn't be sure. She prescribed Deramaxx and rest for a few days. After no improvement, she took x-rays while Oreo was sedated. The tear won't show up on the x-ray. But, apparently, when a dog is sedated, the vet can move the knee a certain way to confirm the tear.

We had surgery to repair the tear because Oreo is a large dog. I've read online that sometimes in very small dogs the tear heals without surgery.

I, too, was worried about giving her Deramaxx because I read awful stories online. But, we did a blood test before we started it to check her BUN and creatnine levels, and then I watched her closely for side effects while she took it.

Anyways, in total, Oreo took Deramaxx for about 5 weeks. It helped her pain and inflamation. But, it's not something I'd want to giver her long-term, because of possible kidney and liver side effects.

I have no experience with Rimadyl, so I can't compare.