Happy the hippopotamus has his tusks filed down by keeper, Anthony Dorrian, at Western Plains Zoo in Dubbo, Australia. The 26-year-old common hippopotamus needs his tusks filed every day to stop him injuring himself. "Happy's lower tusks were growing so long and sharp they were cutting his lips," Mr Dorrian said. "We had to train him to open his mouth for us and hold it open so we can file the tusks down to keep them smooth."

Credit : Newspix / Rex Features