Check out the new arthritis medications available for dogs. They can make a big difference but do your homework and ask your vet a lot of questions first. The links below can help you with your research. Know your dog. Signs of illness or injury can be very subtle.
Pace walks and exercise.
Let your elder dog decide what his limits are. Be prepared to carry your dog if you guess wrong about his stamina. Stimulate their senses with car rides, trips to the park or visits with friends. Just like old people, old dogs still need some excitement in their lives. Make time for cuddling.