Our dog is a Golden Retriever. They are prone to arthritis. They need daily excerise, carpeting on the floor (so they won't slip), warmth and supplements with calcium. The vet can recommend what supplements are best for the dog. We also buy dry dog food that has calcium in it.
My older Golden Retriever has really bad arthritis, and after trying to fix it by controlling his weight with special food, we had to talk to the vet for advice. He ended up prescribing Zubrin, an anti-inflammatory, and it really helped.
I own a Boston Terrier. The best thing that I heard of is giving them condroiton pills.
also see Controlling Excessive Shedding With Cholodin Canine
also see Understanding Canine Osteoarthritis
also see The Classic Dog Arthritis Remedy: Heat Treatments
also see Arthritis in Dogs: What Every Pet Owner Should Know