Just because your senior dog moves with a slower, stiffer gait than when they were a pup doesn't mean they should stop exercising. Senior dogs, especially those with arthritis, not only can exercise -- in many cases, they should. Exercise helps increase flexibility and endurance, strengthens muscles around the joints, and can help stave off health problems caused by obesity. Exercise also aids bowel function, which is especially important in older dogs. And, since obesity tends to make arthritis worse, any activity that helps your dog lose weight could ease their symptoms in the long run. Try low-impact exercises, such as swimming and moderate walking, with your old fellow.