For dogs with OA (osteoarthritis), I would recommend the following nutriceudicals in addition to glucosamine....
1) Chondroitin (often paired with glucosamine)
2) MSM (also often paired with glucosamine)
3) Omega 3 fatty acids with as much EPA (eicosapentanoic acid) as possible
4) Antioxidants
The omega 3 fatty acids also help the kidney function and health which can help the patient deal with the effects of the NSAIDs.
Tramadol is another medication that can be added safely if all the others together are not enough. Also physical therapy, magnet therapy, accupuncture, and K-Laser therapy can help.