Old Age

My Schnauzer is 16, she cannot see very well and walks slowly. She only gets up to go outside and at night, when she is ready to go to bed, she walks in circle around the livingroom. She eats good, but drinks lots of water and now I have to pick up the other dogs bowl or she will eat his too, which is out of character for her. She cannot hear very well either. She was the runt of the litter, yet she has outlived all of her siblings, mother, father, and all of her puppies too. She has been treated like a baby since day one. I believe she has arthritis now and I am worried one day I am gonna be at work and she is going to pass. Any suggestions?