Otto

Not sure if Otto hurt himself here or managed to get some sort of marker onto him.
Any ideas on this?
He was walking fine incidently and didnt seem to be in any bother.

Over a decade late but I think I have an answer to your question. The pygmy hippo has a very distinctive looking oily sweat which looks like blood when exposed to the sunlight and is thus called "blood sweat" so this wasn't a case of "Otto" being injured or wounded but rather of him being sweaty.