>>531355918
What would Oguri Cap's asshole be like? Let's take some factors into consideration. First, her diet. Horses have a digestion time of 72 hours, belonging to a group of non-ruminant, fermentation-based anaerobic digesters known as hindgut digesters. They don't produce as much gas as ruminants, but still produce far more than other animals of comparable size.
Given this, her asshole would likely be highly fragrant, ripe with the scent of fermented carrots, hamburger (Likely rotting by that point), and the sickly, almost lawn-clippings-left-to-rot stench of however much grass she horfs down on a daily basis, as well as sweat from all her races, left to anaerobic bacteria, giving it a more "swamp ass" scent than "regular sweat" one.
Appearance-wise, it's gonna be cute. Because she's cute. A small, pink hole, normal, tight pucker. But susceptible to irritation, blocked hair follicles, etc. due to the aforementioned swamp ass. You should work diligently, preferably with your tongue, to assure any Umamusume's anal health, but especially Oguri Cap's.