First and foremost, talk to your vet about Adequan therapy. (There's also a generic form of it that's a little less expensive...I can never remember what it's called though--your vet should know). Adequan helped me get my dog off Deramaxx/ Rimadyl, and he's better now than he was on NSAIDs! There are lots of threads in the archives about Adequan--please read up on it, as I know of nothing as powerful to help arthritic dogs.
Adequan is a bit of a commitment (shots 2x a week for a month, then maintenance shots biweekly or monthly forever), but when it works, it's AMAZING. It helps the dog regrow new cartilage inside the joint instead of just masking inflammation. It can add quality, active years to your girl, and it's supposed to be very, very safe.
I wish it were recommended early in the onset of arthritis for more dogs, but a lot of vets don't seem to know about it and default to prescribing NSAIDs (my old vet did that too--I had to switch to a new vet to find one using Adequan successfully in arthritic patients). I'm very grateful to the people here who informed me about it--it helped my 11 year old go from a dog who moved slowly and gingerly when he wasn't on NSAIDs to one who doesn't need NSAIDs and is back to wanting to jog and play.
As for supplements, I think they important even with Adequan therapy -- same with regular, gentle exercise (it's very, very important for dogs with arthritis). My vet believes the best results for arthritis are seen with a multipronged approach that works synergistically (exercise, supplements, Adequan...and if needed, very low doses of the safest pain meds). We'll be adding acupuncture into the mix in the coming weeks too, now that I've located a local practitioner who specializes in dogs.
This thread describes the supplements I'm using, and I got lots of great advice in that thread:
I've since added coconut oil to the list.
FWIW, I've come to believe that the Collagen II (chicken sternum) supplement (Twinlab MaxiLIFE® Collagen Type II -- 60 Capsules - Vitacost
), which is high in hyaluronic acid, is important. The bone broth recipe described in that old thread by Gatorbytes inspired me to use this supplement, and I think it's a helpful addition (though one rarely on the standard list for arthritic dogs).