Ergots and chestnuts on horses

Horse chestnuts are a few things – actual nuts that people eat and those crusty formations on the inside of the horse leg. Ergots, on the other hoof, are on the underside of the fetlock joint.

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saxophone shaped chestnut on a white horse

Horse chestnuts and ergots come in all shapes and sizes! These hind-leg chestnuts look like a saxophone.


The lore about chestnuts on horses


  • Chestnuts are sometimes called “night eyes” which is a bit creepy by itself. It was believed that horses can see well at night because of their chestnuts. I can’t pinpoint when this rumor started, but it’s likely before modern ophthalmology. This is also quite the fun fact about a horse’s leg.


  • Some believe horse tales that they are vestigial scent glands. This theory of chestnuts as scent glands perhaps led to a wive’s tale and old cowboy trick that you carry the chestnut peelings of another horse into a paddock, and the horses there will come up to you to investigate, thus making catching easier.


  • Many believe that chestnuts are vestigial toes that have migrated. There’s a bit of conflicting information about this thought. At some point, ancient horses had 3 or 4 toes. Did some of those toes become the splint bones alongside the cannon bones and the chestnuts?


  • Recent evidence suggests that these extra toes, which started out as five total, actually exist in the incredibly early stages of a foal’s development in the uterus to this day. As the foal grows, the toes come together to create a hoof that we know and love. This is called digit reduction – instead of toes becoming other parts of a horse’s anatomy. More science and info on this can be found here.


Do all horses have chestnuts?


  • Most modern-day horses have chestnuts on all four legs. On the front legs, they are above the knee, and on the hind legs, chestnuts are below the hock. Some breeds of horses, namely Icelandic and Caspian ponies, may be missing the hind leg chestnuts. Many horse relatives, like the zebra, don’t have hind leg chestnuts.


What is the purpose of horse chestnuts?


  • Chestnuts on horses are small callus-like growths on the inner side of a horse’s legs. They have no known purpose and are considered a vestigial structure, a remnant from evolution with no current function in modern horses.


large and moutainous chestnut on a black horse

These chestnuts are bananas.


How to care for your equine partner’s chestnuts


  • Many of us like to keep chestnuts flat and tidy; otherwise, they can be a little lumpy and sometimes really pokey and long. The easiest way to keep them tidy is to peel them when they are wet. After a shampoo bath and rinse may be the best time to peel them.


  • Or, you can keep them oiled up with baby oil or moisturizer and peel them after they are nice and soft. Some folks use petroleum jelly to do this.


  • I don’t like the idea of using a blade or razor to remove them. In my hands, this is a recipe for disaster, either cutting too deep or having a wiggly horse dance into a blade. But the truth is I would probably slice my own finger off handling a blade.


  • Some farriers can trim up chestnuts for you.


  • On show day, you can spiff up your horse’s chestnuts with a coat of grooming oil or do nothing and carry on.


  • None of this is necessary! Most horses have absolutely normal chestnuts that don’t need to be groomed, altered, or oiled up. Some horses, who may have supernatural powers, grow such wild chestnuts that they must be trimmed. This is usually necessary when the growth rubs against other legs when sleeping.


What’s “under” a horse chestnut?


  • I never ever ever thought about this until I learned that a friend’s horse came in from the pasture with a big fat let. Cause of this? A suddenly missing chestnut. There’s no bleeding, but you can see from the photo below that there is skin-like tissue below the chestnut.


  • It did grow back to normal after several weeks.


horse chestnut on leg that has been ripped off

This horse lost their chestnut and had a nice fat leg because of it. 


All about ergots on horses


  • Ergots have a similar texture to chestnuts but seem to grow endlessly at the back of the fetlock. For this reason, I absolutely despise ergots and find them to be all sorts of annoying and strange.


  • And who named them ergots? This silly word is a variation of the French word for “rooster spur” which, TBH, is pretty spot on.


  • It’s a bit more interesting to think about where ergots “came from”. The horse’s living relatives of the order Perissodactyla are the tapir and the rhino. Creatures of the order Perissodactyla are odd-toed ungulates, meaning they have hooves of an odd number of toes.


  • These creatures also have hoof pads or the remains of a hoof pad. It’s just as it sounds, like a built-in squishy pad that the hoof rests on. The theory is that the horse’s ergot is the remains of the hoof pad.


  • Most horses have ergots, but some don’t.


ergot on the fetlock of a horse

Ergots range in size from little nubs to these kickstands.


Caring for horse ergots


  • Ergots are also easily removed in the washrack after shampooing and a rinse. Or even just a rinse. Much like chestnuts, you don’t have to do anything with them if you don’t want to!


  • Small ergots that don’t extend or grow much feel like callous or scabs.


  • Use your fingernails to peel the outer layers away. Your farrier might also be able to trim them for you. Using a blade might be dangerous for your horse and your hands.


  • Please don’t twist off the ergots. Many nerves and soft tissue structures meet at the back of the fetlock, where the ergot sprouts. Keep it all where they’re supposed to be, and don’t twist the ergot.


  • One more note about ergots. Please don’t let them turn into gigantic kickstands, or I will hunt you down, peel them off, and then smack you with them—gently.


If you want more horse myths and mysteries, read this article.


A short video about chestnuts

A short video about ergots

A longer video about horse chestnuts and ergots


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