Trollkin from Iron Kingdoms. They are what the name says: kin to trolls. About the same relationship as humans have to gorillas.
They retain a lot of the regenerative powers, so they’re very willing to settle things with violence, because hey, what’s regrowing an arm or two between friends?
They’re big, loud, rambunctious, deeply respectful of nature, and are basically Big Dwarves. Also orcs? They don’t really have an analogue, which is why I like them so much.
It’s probably sick. That’s unfortunately pretty much the only time a wild animal will react like that. I suppose there is an outside chance it’s domesticated and got out of its pen.