A haiku is a traditional Japanese style of poetry that consists of three lines of specific lengths and uses a seasonal reference to describe a feeling.
They're popular on the internet because they're perceived as easy to write, being short with few rules. Sadly they don't make a lot of sense in English, because English doesn't really do syllables of uniform length and stress like Japanese has, so the effect is mostly lost.
When people say "this is a haiku", they mean the syllable counts line up. They're not saying "this is poetry".
Yeah, I think it could work if more attention was drawn to the bear, maybe have the horses all cowering in one corner looking at the bear. I had to read the explanation to even know it is a bear, it's so tucked away.