SYDNEY (Reuters) - A huge cane toad the size of a small dog has been captured in the Australian tropical city of Darwin, startling environmentalists who are fighting to stop the poisonous reptiles from spread across the country. "It's a monster toad," said Paul Cowdy from FrogWatch which captured the cane toad on Monday night. "We've never seen a cane toad this big," he said on Tuesday. "It's a male and normally females are bigger." The cane toad, regarded as a major pest in Australia, was one of 39 caught by a group from FrogWatch near Lee Point in Darwin....