My female GW, Jasper, has severe arthritis in her left foot/ankle, moderate arthritis in her right foot and has recently developed arthritis in the "elbow" joint of her right wing. There are days that she is in a lot of pain and those days seem to coincide with when my arthritis is acting up.
She has been on Metacam for 12 years (with no detrimental effects) and is now at the maximum dosage for her weight. Tramadol is not an option for her, because it is an opium derivative and she also has cardiomyopathy (congestive heart failure) and atherosclerosis (hardening of the arteries). Opiates suppress the circulatory and respiratory systems.
The advice given by the other posters are all included in Jaspers treatment, but she absolutely refuses to perch on the heated perch and she will not sleep on the blanket I put on the floor for her like Hank used to.
Low level laser therapy is a recent development for arthritis treatment in people and animals and my vet has presented this option. The problem is it takes a number of treatments and I live 100 miles from the nearest treatment center and most important, Jasper's overall health is quite delicate right now. Basically, she is at the end stage with her heart and circulatory diseases.
Here is one link to more info on Low Level Laser therapy (there are many more);
LiteCure Companion | Advanced Laser Therapy Systems