I havve a lab that will swim beside for over a half an hour in icy water and does not seem to suffer. Also have a Chessie and he loves nothing better than to swim along with me out in the deeper water. Half the time when we get back to shore he does not even shake off. His coat will turn white with ice and his tongue is still out and he is panting. This was the case just the other day when it was 7 degrees on the marsh. He breaks ice like a miniature bulldozer so putting a life jacket on him would be senseless. There are many labs nowadays that do not have decent coats and I guess these are the ones that really need the vest.