It's getting cold out there, and that means ponds, marshes and rivers are freezing over. Consider the consequences of sending your gun dog out onto the ice. If there's any sense of danger, pass on the retrieve. You may lose a duck, but that's better than losing a great companion.
Sometimes, it's unavoidable that a bird falls over a frosted-over patch of water. Well, in that case, I suggest purchasing a protective vest. You can buy one for less than $50. They keep internal body temperature up and can prevent injury. A shard of ice or an underwater snag can pierce the toughest of retrievers.
Also, get your dog familiar with icy conditions before a hunt. Start off in shallow water and gradually send him on short retrieves until you think he's ready for the real deal. And please, don't send a puppy out into the frozen beyond. His coat is not yet thick enough for such things.
Keep a keen eye on your dog during these cold-weather hunts. The initial stages of hypothermia include: violent shivering, becoming lethargic and difficulty breathing. Should your dog's core temperature drop below 97, or suffer from severe lack of coordination, it's time to take drastic measures. Collapsing and comas are just around the corner, so get that pooch warmed up with blankets, coats, hot pads and even a hair dryer. Do whatever you can to get his temp back up to 101.5, and contact the vet ASAP.