Yeah, essentially a centaur is just a creature with 2 torsos on top of one another. Yeah, they also change species halfway through, but just because you connect a human torso to a horse torso doesn’t mean the horse suddenly pees from its torso. The human digestion system probably connects directly to the horse digestion system. Maybe it’s even got extra stomachs to better process plant material. Either way, there’s no reason to think it just pees out of its horse chest - it needs that space to hold the enormous horse lungs that let it gallop.
Yeah, essentially a centaur is just a creature with 2 torsos on top of one another. Yeah, they also change species halfway through, but just because you connect a human torso to a horse torso doesn’t mean the horse suddenly pees from its torso. The human digestion system probably connects directly to the horse digestion system. Maybe it’s even got extra stomachs to better process plant material. Either way, there’s no reason to think it just pees out of its horse chest - it needs that space to hold the enormous horse lungs that let it gallop.