I've been within a few feet of deer, bear and moose in the wild, never smelled anything (and no, I wasn't fearful). However, I have a pretty poor sense of smell, especially when it comes to musk and dung. I can differentiate horse dung from cow dung in the air inside a stable or when it's being piped onto a field as fertilizer, but I've been known to walk right past a pit toilet without noticing it, when my companions were retching. I can smell wet dog in a house or car, or sweaty horse if I stick my nose under a saddle blanket, but if you say "the smell of horses" [assuming you don't mean horse dung], nothing comes to mind.