What Are Horse Chestnuts? Let's Take A Closer Look...

what are horse chestnuts - horse facts - aspiring horseman

You've started spending more time around horses and noticed these mysterious protrusions on the horse's legs...

...what the heck are these?

On some horses, they are small; on other horses, they are pretty large.

What you are noticing is often referred to as a "chestnut."

This article will delve deep into understanding these peculiar features, shedding light on their purpose, composition, and how to care for them.

We'll also distinguish them from the often-confused ergots.

Short Summary

  • Chestnuts, often considered horses' "third eye," are believed to be vestigial remnants from the evolutionary journey of horses.

  • Horse chestnuts, splints, wind puffs, and capped hocks or elbows are different types of bumps that may appear on a horse's legs for various reasons, including trauma, strain, or stress.

  • Understanding the different features of a horse's body, including bumps like horse chestnuts and a hunter's bump, is a crucial part of horsemanship.

Why Do Horses Have Chestnuts?

why do horses have chestnuts - horse facts - aspiring horseman

Chestnuts, often considered horses' "third eye," are believed to be vestigial remnants from their evolutionary journey.

While their exact biological function remains somewhat of a mystery, scientific consensus suggests that these growths could have once been scent glands, like those found in other animals.

Today, while they may not serve any particular physiological role, they are a unique characteristic of equine anatomy that often facilitates identification, as no two horses have the same chestnut pattern. 

What is a Horse's Chestnut Made of?

These chestnuts are made from the same keratinous substance that forms a horse's hoof. This rugged, horn-like material is primarily composed of keratin, a protein found in human hair and nails.

The chestnut's texture and hardness can vary among horses - it can feel as smooth as polished leather in some, while it may appear more rough and flaky in others.

The size and growth rate of chestnuts can also differ, and these variations are often influenced by the horse's overall health, age, and environmental conditions.

What Are Ergots on Horses?

Ergots are another unique feature found on a horse's legs, similar to chestnuts in their composition of keratinous material. However, they're typically found in a different location - at the back of a horse's fetlocks, essentially the horse's 'ankle.'

Like chestnuts, ergots' size, texture, and appearance vary significantly among horses.

Some ergots are barely noticeable, hidden beneath the horse's long fetlock hair, while others can grow to the size of a small pebble. 

What Is the Difference Between a Chestnut and an Ergot?

horse chestnuts vs ergot - horse facts - aspiring horseman

Chestnuts and ergots are found on horses' legs and have distinctive characteristics.

Chestnuts, also known as 'night eyes,' are horny, irregular growths found on the inside of the leg. They can vary in size and texture, appearing smoother on some horses and flakier on others.

Ergots, on the other hand, are typically found at the back of the fetlock, the equivalent of the horse's 'ankle,' on either the front legs or hind legs; these keratinous materials are often hidden beneath the horse's long fetlock hair and can grow to the size of a small pebble.

Fundamentally, the key difference lies in their location and visibility.

How Do You Get Rid of Chestnuts and Ergots on a Horse?

farrier trimming ergot - horse farrier - aspiring horseman

Removing chestnuts and ergots on horses requires a careful and delicate approach, ensuring the safety and comfort of the horse. It's best done after a ride or bath since the horse's skin will be warm and softer.

Start by gently peeling off the loose layers of the chestnut or ergot. If they are particularly hard, soaking them beforehand in warm water or a mild horse-friendly oil can help soften them.

Be mindful not to forcefully pull or cut them, as this can cause discomfort and potential harm to your horse. If you're unsure or uncomfortable doing this, it's always best to consult a professional equine vet or farrier.

We have an older horse with very pronounced chestnuts on his front legs. Once in a while, the farrier will trim them back when he is out trimming hooves.

No big deal.

Care and Maintenance

Caring for and maintaining horse chestnuts is an integral part of good horsemanship. Regular grooming is crucial, enabling you to monitor any changes in their size or condition. Use a soft brush to clean the area carefully, removing any dirt or debris that could cause irritation or infection.

Hydration is also key for the maintenance of them. While too much moisture can cause the chestnuts to become too soft and prone to tearing, they should not be allowed to become excessively dry, either.

If the chestnuts on your horse's legs appear particularly hard or dry, applying a mild, horse-friendly moisturizer can help maintain their elasticity and prevent them from cracking or becoming uncomfortable.

Lastly, while many horse owners feel comfortable maintaining their chestnuts, having a professional (like your farrier) handle the task is never bad.


In conclusion, understanding horse chestnuts' peculiarities and care techniques is another critical piece to the horsemanship puzzle.

Regular maintenance and keen attention to changes can help ensure the health and comfort of your horse's four legs.

Remember, your horse's well-being is not just about the ability to ride but also about fostering a relationship rooted in care, knowledge, and dedication.

Embrace your horse-owning journey with curiosity and commitment, and don't hesitate to ask questions or seek help!

Frequently Asked Questions

Should I take my horse to a Vet for an ergot or chestnut on their leg?

It is recommended to consult a vet if you're unsure about any changes you've noticed on your horse's leg, including ergots or chestnuts.

These growths are generally harmless and part of a horse's natural physical traits. However, if you notice any abnormal changes, such as swelling, discoloration, or excessive growth, or if your horse exhibits signs of discomfort, it's essential to get a professional opinion.

Remember, it's better to be safe than sorry regarding the health of your horse's legs.

What do protein bumps look like on horses?

Protein bumps on horses, also known as equine sarcoids, typically appear as small, round lumps on the horse's body, often on the legs. These bumps can vary in size and may have a rough, warty surface or a smooth, hairless appearance.

In some instances, they might even resemble a flat, scaly patch. The color can range from skin-toned to dark brown.

While these bumps are generally not painful or harmful to the horse, it's crucial to consult a vet if you notice any unusual lumps or bumps for proper diagnosis and treatment.

What's that weird growth on my horse's leg?

That weird growth on your horse's leg could be a horse chestnut, also known as a "night eye."

Horse chestnuts are natural, harmless callouses that can be found on all horses. Typically, they are located on the inside of a horse's front or back legs, above the knee or hock (the equivalent of the human ankle). The size and appearance of horse chestnuts can vary among horses.

Although they appear unusual to horse novices, horse chestnuts are a normal part of a horse's anatomy and are generally not a cause for concern. 

What are the bumps on a horse's leg?

The bumps that you may notice on a horse's leg could be several things.

They could be horse chestnuts (the natural growths we discussed earlier) or splints—bony growths that occur on the inside of a horse's leg, usually due to trauma or strain.

They might also be wind puffs, soft, fluid-filled swellings typically found around the horse's ankle, and often occur due to stress or injury.

Another possibility is capped hocks or elbows swellings on the points of the hocks or elbows, usually caused by trauma.

Each of these bumps is unique and may require a different approach in terms of management or treatment.

Always remember, if you notice any new growth or swelling on your horse's legs, it's prudent to seek advice from a vet.

What is a hunter bump on a horse?

A hunter's bump on a horse is a noticeable protrusion on the top of the horse's hip, specifically where the pelvis and spine meet.

This bump, also known as a sacral tuber, is more prominent in some horses due to its skeletal structure or muscle condition. However, it can also be a sign of a skeletal misalignment or injury, often resulting from a horse repeatedly arching its back.

It's commonly seen in jumping horses, hence the name "hunter's bump."

Like with horse chestnuts and other leg bumps, it is best to consult a veterinarian if you notice a significant change or if your horse shows signs of discomfort.