Degenerative joint disease (osteoarthritis) and pain therapy?

[Catherine L]

Our 7 year old cocker spaniel, Bismark, is plagued by what was determined last year to be degenerative joint disease (osteoarthritis). The x-rays show that the cartlidge in his knees is almost completely gone. He has his good and his bad days, but lately, more bad than good. Originally, our vet prescribed him 30 days of an anti-inflamatory and told us to give him glucosamine on daily basis. He won't treat with pain meds for long periods, but the gloucasamine hasn't improved his mobility at all. Should I start over with a new vet (we've been taking our 4 dogs to our current vet for 9 years) or should I simply try to order the pain meds online (I think it was Rimadyl)? Do you have any suggestions for other forms of pain management?