The very first keep I ever used was a swim keep, on Truman, because he refused to run (or even handwalk) a long distance. He also refused to chase a hide.

A swim keep was the only thing I could think of to keep Truman "active enough" to get anywhere near what I would call "conditioned" ... and it didn't work so well for me.

I was green as a spring meadow at the time, so maybe I could have done a better job, but in the end I felt he would have been in far better shape had he just wanted to run instead. (The same is true for boxing or MMA training: running to get in shape for a human fight is simply FAR better than swimming.) Part of a dog deal is being on your feet, and I don't think swimming addresses this at all; in fact quite the opposite.

I would only use swimming as a last possible resort, and even there I would seriously consider using another dog who runs instead.

Jack