@ajmcwhipsnade
Sorry for the delay in responding to your question; I've only just noticed it.
Walk down the road with the yak paddock (previously onager paddock) on your left and the sloth bear exibit on your right.
When you reach the end of the yak paddock continue walking in the same direction (i.e. don't follow the path to the left towards the Indian rhinos); this will take you to the Przewalski's horse enclosure.