Kai McKenzie, 23, was surfing off New South Wales in Australia when he was attacked by a shark, New South Wales police said. “Clinging to life, he was able to catch a wave back to the beach,” a fundraising site set up for McKenzie said. “A retired police officer used his dog’s lead as a tourniquet to stem the bleeding before the victim could be airlifted to hospital.”Amazingly, McKenzie’s leg washed up on the beach after…