I got flamed pretty badly on FR a few years ago from a similar story. The dogs were struggling in icy water.
I suggested that while it was a good training exercise, the more humane thing to do for such a panicked and suffering animal would be to dispatch it 100 yards away rather than risking human life.
As I recall, in the story I commented on there were two dogs and one died a pretty horrible death
You were justifiably flamed.