I thought it was hay or feed of some form, and the horse gas just yanked it's head up in alarm, leaving an arc of feed in the air.
Looking closer, that would have to be sawdust to be that consistent in texture, and even actual bodily fluids don't leave such a sharp edge on a puddle.
I saw that and didn't know horses can't puke, but thought it was fake but because the parking lot was empty of lights, paint stripes for parking, bollards, etc. it's a vacuum behind the horse.
In German there is this kinda obscure phrase „Pferde vor der Apotheke kotzen sehen“, which translates to „seeing horses puke in front of the pharmacy“ used to denote something highly unlikely, because horses can’t puke and especially in front of a pharmacy where they could get something against their nausea.
I don't even think the back legs look too weird. One of the things I've found when trying to spot AI is that often actual images look weird like this just because of the angle / compression etc.