Thousands of fans have flocked to a Thailand zoo to celebrate the first birthday of Moo Deng, the baby pygmy hippo that's become a social media sensation.

By Thursday afternoon, the number of visitors to see Moo Deng reached 12,000, zoo director Narongwit Chodchoy said.

Totally unfazed that it was her birthday, she wandered around her enclosure, took a few naps and chewed her caretaker’s knees while she was hosed down.