I interpret your "
My horse always does a few sloppy poos a week .." to not mean daily, but every few days.
If my interpretation is correct then I would be searching his pasture /paddock existence to what he may be eating that changes his consistency of appearance that it is concerning to you.
Sloppy poo to me is flops, wet plops and less shape and consistency seen.
@kenzie_bork you just said, "The runny poo looks dry and" .... That
doesn't fit my idea of sloppy poos. It's either sloppy or just different appearance but your description of "runny poo looks dry" makes me

Chaff hay can be many different hays combined also makes me think something eaten is setting the gut "off".
🐴... jmo.