There are many reasons why horses might need shoes. There’s pretty much only one reason why cows don’t.
Cattle - Wikipedia
horses - Trivia, Quizzes, and Brain Teasers
Why Do Horses Need Horseshoes?
Why Horses Need Shoes - Mountain Creek Riding Stable
What Is Cordovan? - Henry A. Davidsen
Why Do Horses Need Shoes But Not Cows? - Christophe Garon
To Shoe or Not to Shoe?
Why Do Horses Need Shoes? Horseshoes Do Serve a Purpose
Why does a horse need shoes? - Equestrian Surfaces Ltd