It happens all too often. It's not that they all can't swim, it's that they're a mass of muscle in a dense compact body like a block brick. My husband's friend had a friend's who bulldog jumped off their boat while they were on the lake and unfortuantely it sank to the bottom and they never found it. That was a few years ago.
Oooh my gawd that just made me so Sad to read. Wow, just like that.