Owing to the fact that horseshoes are both a game and a good luck charm, most people know what horses’ “shoes” look like. Exactly why they sport these semicircles of metal (or other materials), however, isn’t quite as widely known.
The simplest answer is that horses wear shoes for the same reason we do—to protect their feet from getting injured due to rough terrain and/or overuse. Horse hooves are admittedly a lot more durable than human trotters: The hoof wall, which covers the top of the hoof and forms a rim around the bottom, doesn’t have any nerves or blood vessels. Horses can safely walk on their own four hooves, wearing down their hoof walls as they go. For wild horses, this process typically happens at a good, gradual rate as they traverse natural terrain.
But, as Horse & Country explains, domesticated horses perform a variety of functions across a variety of surfaces—and there’s a variety of reasons why many need shoes. For some, especially those that pull carriages or bear other loads, their hoof walls might wear down more quickly than they can grow back, which horseshoes can help prevent. Others might need horseshoes for traction if they’re frequently exposed to icy, wet, or muddy surfaces.
Then there are those with medical conditions like arthritis, laminitis (a problem with the connective tissue between the hoof wall and the nearby bones), or ringbone (a degenerative joint disease that causes extra bone growth). Some horses just have naturally weaker hooves or uneven gaits. In all these cases, horseshoes can help stabilize and strengthen a horse’s hooves, and also keep them healthy.
That said, there are horses that fare well with no shoes at all, or only need to wear them occasionally. Farriers—who shoe, trim, and generally maintain horses’ hooves—can help horse owners determine the best course of action and the best type of horseshoes to use. Though some people are staunchly anti-shoe, preferring the natural route, it really depends on the individual horse’s needs.
“A lot of times people talk about barefoot versus shod as if it’s a competition,” Esco Buff, owner of Esco Buff’s Professional Farrier Service, told Practical Horseman. “It’s not one or the other. It’s what’s best for the horse.”
So Why Don’t Cows Need Shoes, Too?
Basically, cows just aren’t expected to do as much stuff as horses are (and across such a wide variety of terrain). We don’t race them; we don’t use them for ranch work à la Yellowstone; we don’t make them carry tourists around Central Park in carriages; and so on. Back when oxen were a common draft animal for farm work, even into the 20th century, they were often shod [PDF]. Since oxen, like cows, have cloven hooves—split into two—they actually wore two separate “shoes” on each foot.
But even though cows can usually function fine au naturel, their hooves still need maintenance: They should be trimmed roughly twice a year, though it depends on the cow.