Interesting facts about horse hooves
- Horses are totally weird, and their hooves are even more so. What sort of mythical creature has his entire body weight supported by tiny little bones? Inside of one single toe?
- And now I give you more reasons that #horsesareweird and at the same time, #horsesareamazing. Specifically when talking about their hooves!
Who are the evolutionary cousins of horses and what does this have to do with hooves?
- The closest relatives to horses are other odd-toed hoofed animals. Seems like there would be a lot of these, but really it’s just rhinos and tapirs. Horses and their relatives are all part of the taxonomic order perissodactyls, which are characterized by one and three-toed creatures that stand on hooves. Hooved creatures are called ungulates, in case you were wondering. The tapir and rhinos actually have three toes, so in that respect, horses are the odd creature out.
This is a tapir, standing about 3 ft tall at the shoulder.
And what are ergots? How do they relate to the horse’s relative, the tapir?
- This sort of leads us into the discussion of ergots, from the French for “rooster spur”. Ergots are growths are on the back of the fetlocks of some horses. Aside from being my personal pet peeve if they are allowed to get long, ergots are of questionable usage on the current day horse. When you look at the tapir, they have three toes and a hoof pad that starts at the rear of the hoof. It grows down and under the hoof in the tapir, and it’s thought that the horse’s ergot was once the horse’s hoof pad.
How many toes did horses have long, long ago?
- You may have heard that the horse’s hoof evolved over time from five toes down to one toe. There’s quite a bit of fossil evidence about this, but maybe not the way you originally thought. I had Iearned that the middle toe became the hoof, two of the other toes became the splint bones, and the last two toes became the ergot and the chestnut. But there’s ample evidence that the split bones used to be PAIRS of toes. So, on one leg, the middle toe becomes the hoof, and the left two toes become the top and bottom of the left splint bone. Same for the right. Still no word on what the heck chestnuts are doing, but you can learn more about them here.
The frog. What is up with the horse’s frog!?
- This structure of the horse hoof has so many jobs! Like why can’t some of the other parts of the hoof pick up some slack here? The frog is known as the second heart of the horse, as it’s a key player in getting blood up the leg. Against gravity. Without the help of muscles in the horse’s lower leg. Because there are none.
- So WHAT is going on? Inside the hoof, there’s a collection of vessels called the venous plexus on both sides of the hoof. When these veins are compressed, the blood inside of them pushes up the leg, back towards the heart.
- The horse, as he steps down, squashes the frog a bit, which presses up to the plantar cushion inside the hoof. This cushion then squashes the venous plexus and blood starts to travel against gravity. All of these vessels and pads also serve to protect the coffin bone inside the hoof.
The frog is the triangular part at the rear of the hoof, bordered by grooves. It’s spongy because of the high water content.
- As it turns out, your horse’s frog does not need to touch the earth in order to work. The downward pressure of your horse’s body inside the hoof also helps to empty the venous plexus and pump blood against gravity.
- This is part of the reason that movement is great for horse leg and cardiovascular health. And also part of the reason that horses can stock up. This can happen to horses that don’t move around much, and it’s more common in the hind legs as they are further from your horse’s actual primary heart.
- The frog also helps your horse get some traction on the earth, which is handy to have. The expansion of the heel is also helped by the frog. And perhaps the weirdest of weird things about the horse’s hoof is that the frog can sweat. True story!
- Oh wait, one more weird thing about the frog. It’s about 50% water!
WHY does the frog sweat?
- You may have noticed that horses tend to be super sweaty creatures. As it turns out, your horse’s frogs also sweat. It’s a slightly different type of sweat gland than what makes his body sweat, and there is not a lot of information about what on earth is the reason for this. It’s possible that a horse’s frog is used as a scent gland so buddies can find each other. Remember those weirdo chestnuts? They might also be some sort of scent gland. Perhaps.
But where does the hoof grow from?
- Fair warning – there’s a yucky photo of a hoof injury below. It’s an older injury and has started to heal, but still.
- The hoof wall grows out of the coronary band, much like our own nails grow out of the nail bed. Fun fact about the coronary band – damage here can create a damaged hoof. Sometimes forever.
- Taking a quick trip into the coronary band and the hoof. The coronary band is the line of tissue joining the leg and hoof, and is made up of an inner layer called the coronary corium. It’s full of blood vessels, and its major function is to feed the hoof.
- Now imagine papillae shooting out of the corium to the ground – these are hair-like structures that carry the nutrients your horse’s hooves need via tubules. These tubules spiral down towards the earth.
- As cellular turnover happens inside the corium, the older cells are pushed out to die. But not in vain – they basically become keratin that forms new hoof. The base and sides of the papillae also make keratin and start to glue things all together, creating the intertubular horn.
- So – if the coronary band is damaged, this process can be damaged and the hoof may never grow correctly. Some horses are fine, others are permanently lame and unrideable. It’s always a big deal to have an injury or sore on the coronary band.
This injury occurred just below the coronary band and resolved completely with no lasting damage. A few centimeters up might have been a different story.
Take extra care of your horse’s hooves – they have a lot of responsibility to keep your horse healthy and sound!