
Something stronger may be in order then. Personally I've never found any of the variations of loxicom (of which meloxidyl is one) all that great and there are many other anti-inflammatory options that may help (rimadyl, previcox, trocoxil, onsior, PLT to name but a few), as well as stronger painkillers such as tramadol.
For my dogs I use golden paste (a turmeric/coconut oil/black pepper recipe) which is a very potent natural anti-inflammatory remedy and so far, I've found it better than any conventional stuff but of course, every dog is different. One of my wonkies needs tramadol alongside it as alone, neither drug is effective enough but together they work well for her (the tramadol is mainly for her slipped disc but it helps considerably for her arthritic feet). Often a combination like that does help a lot, and on the supplements side, there are dozens of things you could try.
I will say that at 10yrs old, as I'm sure you're aware, for a DDB you're looking at quality over quantity at this point, but that does not mean you should just give up - there are so, so many options these days. Have you tried any complementary therapies, such as hydrotherapy or acupuncture?