I had a GSP some years ago. Female, 45 pounds, great hunting skills. I decided to get her a vest for waterfowl hunting although none of our dogs had had them before because she was small. My father and I took her out to a duck lake on a very cold day. Hunting was good and Maddy was retrieving all the birds because there was only one other dog there and it wouldn't swim. When the other blind, a ways away would shoot a duck, we would release her to retrieve it and she would take the duck to that blind before returning to us. Mid day, she headed out to retrieve a duck for the other blind. That put her out of voice or whistle commands but she could still see me good enough to be directed by hand signals. I got her near the duck but she did not come in like I expected her to. I left the blind and started running in her direction but by then she was chasing a duck that was swimming well. She got way out of range and we were helpless as she chased the duck farther away. After about 10 minutes, she gave up and swam to the other shore. She came running back across the dike but about half way across her legs folded up as she was running and she collapsed. We were already running toward her. When we got to her, my father handed me his gun and picked her up and started running to the car about a mile away. When I got to the car, it was running with the heater on full and my father was wrapped up in a blanket in his underwear with her. After about 20 minutes she stopped shaking and after an hour he got out with her and she was fine. I was trying to think what I would tell my wife and children. When we had gotten to her, she could barely lift her head to look at me and I thought that I would never forget the look in her eyes. I believe that without the vest she would have died. It was the best purchase decision I have ever made. I'm now shopping for a vest for my current GSP, a 57 pound boy that is my 24-7 companion. The cost of a vest is so trivial compared to the thought of losing my dog or even him being cold when he doesn't have to. When you think about going home to your children without their dog, it's not even a choice.