>>86637A bought lifejacket is presumably designed to keep the animal's head above water when it gets tired (the flotation goes around the neck too, not just around the body). A floating dog pack wouldn't be as effective. I guess it depends on the risk of capsize or the dog jumping out, and how good a swimmer your dog is. I don't have any personal experience paddling with dogs though, I didn't have a boat when I had a dog.
My old lifejacket that came apart at the seams was full of closed cell plastic foam.
