GoneDiving
Guru
My lab could swim but hated it. He would sooner dig his claws into me and use me as a float.
There are many cases of panicked swimmers drowning well intentioned rescuers. I don't see why large animals would be any different.
Back on track, even if there are others in board, I'd see an immediate/quick alert of a MOB as a good thing rather than relying on the incident being seen and relayed by others. For solo sailors, it would be a life saver. Even swimming a mile to a stopped vessel Is better than watching your vessel continue to follow it's auto pilot.