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Why Do Horses Have Chestnuts and Ergots on Their Legs?

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One of our older horses’ has chestnuts and ergots that are very apparent, which stirs my grandchildren’s curiosity. They routinely ask why does he have them and what are they for. So I decided to do some research to provide an answer.

Horse chestnuts and ergots are callous on a horse’s legs. Chestnuts are believed to be remnants of an extra toe lost through evolution. They are flat and crusty areas devoid of hair. Ergots are callous growths located at the bottom of the horse’s fetlock, often covered by hair.

Chestnuts and ergots are, for the most part, cosmetic and typically require very little attention. However, it’s beneficial to have an in-depth knowledge of horses if you have to answer your child’s questions.

Grooming gloves are useful to wear when removing chestnuts. Click on the ad below to learn about the innovative grooming gloves made by HandsOnGloves.

Picture of a horses' chestnut

What is a chestnut on a horse?

If you notice a bare rough patch of skin on your horse’s leg is likely the animal’s chestnut, and be assured it’s normal. These bare spots are not a health risk unless injured and bleeding.

Some scientific studies indicate chestnuts and ergots are inherited from the earlier species of the multi-toed horse known as the “Equidae. ” These types of horses are descendants of the “Eohippus.” a modern period ancestor of around 40 million years ago with vestigial toes.


Researchers believe horses evolved slowly, and the extra toe lost its functionality, shrank, and became chestnuts and ergots. The third toe theory is just that, a theory it’s not accepted as fact.

Chestnuts are located on horses’ legs.

The chestnuts typically appear on your horse’s front legs just above the knee and just below the hock on its rear legs. They can seem quite large or be small, but most are scratchy, flat, and devoid of hair.

Much like a snowflake, a horse’s chestnut pattern is unique to every horse. Horse chestnuts are also known as the “Night eyes” based on the lore that they provide an ability to look around in the dark.

Are chestnuts different from the ergots?

Not all horses have ergots, and some horses may have them only on one or two of their legs. If your animals have ergots, they are on the back area of the horse’s fetlock, usually covered by its hair.

Because the hair is usually long in this spot, ergots are often challenging to see. But if you rub beneath the horses’ fetlock, you will feel them; they are narrow and pointy.

Ergots feel like a rough protruding structure coming down from the fetlock. They can usually be peeled off with your fingernail, but you can use a sharp knife if necessary.

I would advise having your farrier check the ergot and take care of it before using a knife to cut it. Ergots can vary in size from the size of a bean or pea to 1.5 inches in diameter.

Unlike chestnuts, ergots can be significant on the forelegs and much smaller or not present at all on the hind legs.

Picture of a thoroughbred racehorse.

Can I trim the chestnuts?

Chestnuts are located on the inside of the horse’s legs, and they are living tissue that continues to grow throughout the horse’s life.

Because they always are growing, they need to be maintained by trimming or peeling, this can be a painful process for the animal, so extra care is required not to hurt your horse.

In the video below, Rick Gore shows how easy the chestnuts are to peel. Most chestnuts don’t require trimming but rather just peel off layers to flatten them out and look cleaner.

You can use a knife or a similar tool that can scrape the area relatively easily when wet. I find that peeling the chestnut or trimming is made much easier when wet.

But always stop if your horse starts to signal you’re hurting it because if done correctly, the process should be painless. You can also apply petroleum jelly or baby oil to remove hard chestnuts.

Picture of a horse standing on stall mats in the wash rack.

Don’t twist the chestnuts; this causes pain and often makes the chestnut bleed. Pulling off a dried chestnut is another way to cause bleeding.

Grooming chestnuts

For show horses, the chestnuts should be neatly groomed to make your horse look well maintained. It’s the attention to detail that matters. When grooming your horse, peel or trim the chestnuts.

To peel your horse’s chestnuts, you can use your hands and fingernails. First, soften them with water, baby oil, or moisturizer so they are easier to remove.

After you finish, you can enhance the appearance of your horse’s legs with petroleum jelly. Applying petroleum jelly regularly keeps the chestnut tissue soft and makes maintaining it more manageable.

The tissues present on the chestnut’s base will bleed if you pull off the chestnut’s dry layer. On some horses, chestnuts are hard or become unsightly over time; in this situation, clipping them with a pair of nippers might be a viable option and won’t hurt your horse.


At the same time, if you use a razor or blade to remove them altogether, you may end up hurting your horse by cutting it too deep or close to the skin.

You should talk to my farrier if you aren’t experienced in clipping chestnuts. Most farriers will clean up chestnuts when shoeing horses.

If your horse’s chestnuts show exuberant size or growth, it can be an indicator of bad health like laminitis. Laminitis is a painful condition for horses and can have much more significant welfare implications for the owners as well.

Laminitis is the tissue bandings’ inflammatory condition that may be recurrent for individual horses.

You can use the following process to take care of the horse’s chestnuts:

  • Apply petroleum jelly on the surface of the chestnuts before and after trimming or peeling the chestnuts.
  • You can also apply a hoof moisturizer to the chestnuts. After some time, the chestnuts might split into chunks, making it even easier to maintain the chestnuts.
  • During regular grooming, peel off excessive growth
  • If your horse begins to bleed at the site of the chestnut, apply antiseptic
  • Follow the application of antiseptic with a water-resistant and breathable seal of liquid bandage,

Both chestnuts and ergots can be taken care of with just your hands without much pain. There is no reason to peel them off entirely, but some horse owners do it for horse shows.

Interesting chestnut facts

  • Zebras and donkeys have no chestnuts on their legs
  • The appearance of a horse’s chestnuts often changes
  • Chestnuts are similar in appearance to the wrist pad of dogs and cats
  • Horse chestnuts look similar to vestigial scent glands found in the deer and some other animals
  • Chestnuts, when scratched with your fingernail, will release an excellent peppery musky smell.

Most horses have chestnuts on all four legs, including the last known “wild horse” breed, the Przewalski, but there are a few horse breeds that don’t have any chestnuts on their legs:

  • Caspian pony 
  • Banker horse
  • Icelandic horse

Below is a YouTube video about horse chestnuts and ergots.


Should you cut off or trim your horses’ chestnuts?

You really should leave your horses’ chestnuts alone. But if they look unsightly and you want to trim them, you can. Just don’t cut deep or use your fingernails to peel them.

What is the purpose of a chestnut on a horse?

The chestnut doesn’t serve any practical purpose for the horse. However, some breed registries use it as an identifier because each is unique, like a human fingerprint.

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