I've had a couple of smaller litters with fat puppies that looked like they wanted to trend toward swimmers. I'll put egg crate foam mattress pads under the whelping fleece to make for a soft but irregular turf for them to manuever on. I had one little fella that I would lay on my lap, on his side, and just massage his rib cage from his back toward his belly for a while in the evenings much like one of other posters has described. He was slower to walk at first but it didn't take long before he was up and about with the rest of the litter.
