Swimming is often recommended as an alternative exercise for arthritic dogs because of the low impact it places on your dog's joints. (1800petmeds.com)
(In fact, walking can be beneficial in arthritic dogs as it helps to maintain muscle mass and distribute joint fluid, which keeps joints lubricated). (nomnomnow.com)
This would help arthritic dogs avoid carrying extra weight on their joints if they are at the proper weight. (darwinspet.com)