There are many reasons why horses might need shoes. There’s pretty much only one reason why cows don’t.
He keeps taking off his shoe! Overstepping? : r/Horses
What happens when you don't trim your horse's shoes. : r
Mental Floss
Farrier supplies and tools for the part-time 'shoer' - Progressive
Should Horses Be Barefoot or Shod
Why Don't Wild Horses Need Their Hooves Trimmed? - KAKE
Oxen, Mules & Horses - Oh My! California Trail Interpretive Center
The Bad And The Ugly – Halter Horses
HORSE SHOE - リング