I have a two-month old calf that for the past couple of days is not putting any weight on one of it's back legs; if anything, the tip of the hoof will occasionally touch the ground. There is no swelling and no bones showing through. Otherwise, he acts fine; he has plenty of energy, and he even runs at times. Does that sound like the symptoms of a fractured bone or something else? Could a calf walk if it were a fractured bone, or would he be down in a lot of pain?