You may use ARTHRO-IONX or PROMAXOL along with other medications or supplements so it is OK to use with Rimadyl. It is homeopathic in nature and so it will not negatively interact with other physical substances. Give ARTHRO-IONX away from pharmaceutical medications. When you begin to see some improvement talk to your veterinarian about decreasing the Rimadyl. It can stress the liver. You might want to Google side effects of Rimadyl.
To dose ARTHRO-IONX I would split the dose and give a half dose with breakfast and a half dose with supper. In addition I would give PROBIOTICS, vitamin C, OMEGA 3,6,9 and MSM. What kind of water and food do you give your dog? These can influence joint health too.
I would recommend having a veterinary chiropractor check your dog. It often improves movement. Acupuncture can also be helpful.
Please let us know how you do.,