Agree with Patty,
Seniors need more quality protein and most “senior” foods have a reduced amount of protein and an increased amount of fillers or grains which are actually more inflammatory. There are some exceptions like Amicus Senior, Merrick Classic Senior, Orijen, Blue Buffalo Wilderness Senior and a few others. But I would stick with an “all life stage” food with at least 30% protein.
http://healthypets.mercola.com/sites/healthypets/archive/2011/05/05/surprising-findings-from-tufts-study-of-37-senior-dog-foods.aspx
There are several options to help with joints: green lipped mussel, omega 3, tumeric, Wysong Arthegic, Actiflex 4000, glucosamine, MSM, chondroitin, tart cherry, Esterifiedd fatty acids like cetyl-myristoleate, Yucca http://www.1800petmeds.com/Yucca+Intensive-prod10850.html
http://www.coxvetlab.com/products/acti-flexk9.htm
