The phrase "horse armor" refers to protective gear or clothing specifically designed to keep a horse safe from harm or injury during activities such as riding or racing. Full definition
Reading through a 2006 story I wrote about horse armor — please excuse the poor writing, I was only 21 — is fascinating. (waypoint.vice.com)
While expansion packs had been offered in the past, downloadable content became the norm for nearly every game, delivering everything from horse armor to new characters, maps, and more. (1up.com)
Horse Armor DLC for Elder Scrolls Oblivion, and everyone laughed at that time on these things. (illgaming.net)