There's plenty of centaur manga out there from the critically well regarded works of Est Em, to the Seven Seas licensed A Centaur's Life by Kei Murayama to sketchier, ero works. "The Outbreeding of an Era" doujinsh from Z-Ton of the SHIS circle falls into the later category. A sequel made some waves at this weekend's Comiket 84, where it was sold along their Blue Submarine No.6 doujinshi "Myu Hearts," but those were nothing compared to accompanying , unique centaur hug pillow they prepared.
Some safe for work material
More not safe for works previews of the artist's centaur doujinshi and Blue Sub No. 6 work can been seen on their Pixiv page.
There's also a hype movie, with a NSFW cover image on Youtube.