Widerange, I would say what you describe is hypothesis as it's something you've never done.

Widerange, what if you swam the dog up and down a river for 2 hours, and you did it for longer sets of time. What if you were able to ultimately swim the dog for 2 hours straight? If you limit yourself from trying anything, you stay trapped within your own man-made box of ideas. Now, I'm not saying you could swim a dog for 2 hours straight, because as I've said, I've never utilized the swimming in a keep. BUT, if you were, I'd say that's a pretty tough thing to do, and while you dog may not be in 100% shape, hell, what dog ever is?