Arthritis, or more correctly, osteoarthritis or degenerative joint disease (DJD), is a common condition in dogs and a rare condition in cats. Arthritis technically means "inflammation of the joint." Inflammation is characterized by swelling, stiffness, and pain; therapy is designed to counteract these effects of inflammation. When possible, the therapy should also slow down the progression of the arthritis, or, actually help the joint to heal.
A joint is the space between two...