A dog rids itself of excess water simply because of that. It's excess. Rubbing one down won't contribute to the urination. If the dog doesn't have enough water, there won't be any excess to essentially urinate. If your dog isn't getting enough water throughout his keep, you won't be able to pull any excess of him. The body will hold onto the water it has instead of ridding itself of the water. You essentially have to hyperhydrate your dog to do what you're asking.