LIVERPOOL, England (AP) — A seven-year-old horse had to be euthanized Friday after breaking its back on the final fence of a Grand National steeplechase race that it won despite suffering the serious injury. It follows the death of four horses at the Cheltenham Festival in March — including one after the prestigious Gold Cup . Gold Dancer was competing in the Mildmay Novices’ Chase during Ladies Day at Aintree’s Grand National Festival. The horse managed to cross the finish line approximately