How Many Hearts Does A Horse Have?

The heart is a vital organ in human beings and animals as it pumps blood around the body through arteries. As you may know, some animals have more than one heart, which makes horse lovers question how many hearts do horses have? There are a lot of myths and age-old sayings about the horse heart. 

These phrases and myths have misled many people into believing that horses have multiple hearts. Is it true? Do horses really have more than one heart? So, many people are interested to know more about this topic, ever wondered, what makes the equine heart so special. 

Horses have a big heart both in size and functionality. It makes sense that a horse has a big heart given the animal size.

Putting aside all the myths and sayings, here, you will find true and valuable information regarding the equine heart.

It would be fun to know more about your favorite animal and its most vital organ. Read on to know how many hearts does a horse has?

How Many Hearts Does A Horse Have?

Just like human beings and mammals, horses have only one heart in their chest for pumping blood. It has four chambers along with inflow and outflow vessels. The heart is one of the most impressive muscles in the horse’s body as it supplies blood to all parts of the body without taking a break. 

It never stops working, whether working or at rest, from birth till death. No other muscle has a bigger workload than the equine heart.

Horses are known for their large heart which if rumors are to be believed is to capture human hearts. Besides that, this hollow muscular organ has two major functions to perform.

One is to pump oxygen and nutrient-laden blood through the body and the other is to remove waste such as Carbon Dioxide.

There are many other features that make the equine heart special and unique.

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Truth Behind “A Horse Has Five Hearts” Saying

Most equine lovers have heard about this age-old adage at some point in their life. It has misled many people into believing that horses actually have five hearts.

Though they have one actual heart, the reason why this expression got popular is that most people believe that horses have a heart in each hoof. 

When the hooves are in the natural barefoot state, the frog in each hoof pushes and pumps blood back in the leg.

The blood is pumped back up with each step a horse takes. The blood pumping mechanism in the hoof is the reason behind this saying. 

Once the hoof is in the weight-bearing phase of the stride, the bare hoof creates a slight vacuum by expanding a little that draws and collects blood in the hoof capsule.

When the hoof is lifted, it comes to its original position as the wall springs back to the smaller resting space. It pushes the blood back up into the leg and to the heart. 

Every twenty strides, about a liter of blood, is pumped through the body. That’s why each hoof is considered a heart.

This hemodynamic action also acts as a shock absorber. Pumping blood through hooves is not possible when the horse is wearing a horseshoe. Horseshoes somewhat restrict blood circulation.


Components Of A Horse Heart

Similar to the human heart, the equine heart constitutes four chambers; the right ventricle, left ventricle, right atrium, and left atrium.

The right atrium takes in oxygen-depleted blood whereas the right ventricle pumps blood into the lung to refill with oxygen through the pulmonary artery.

The left atrium receives the oxygenated blood and the left ventricle distributes and sends the rejuvenated blood to the body through the aorta. 

The horse heart is composed of a special type of cardiac muscle or myocardium. The cardiac wall is made of the majority of the myocardium responsible for all the pumping action.

It contains pacemaker cells which are specialized cells found in the right atrium.

They are a bit different than the usual cells and have an inherent rhythm that sends electrical signals to set the pace for blood pumping and coordinating heartbeats.

Blood Volume

About 32 ounces or a liter of blood is pumped with each contraction. When running or during exercise, the blood volume pumped by the heart increases by 50%.

To meet the oxygen demand, the heart increases the contraction frequency as well as the blood volume. A horse’s body houses a total of 14 gallons or 50 liters of blood. 

Heart Beat

On average, a horse beats about 20 to 30 times in a minute. When running or during any physical activity, the heart rate increases dramatically and rapidly. The horse’s heart rate increases eight times during exercise. The normal heart rate for an adult horse is

  • 20 to 40 beats per minute (bpm) at rest
  • 80 bpm when trotting
  • 110 bpm in canter
  • 140 bpm in a fast canter
  • 180 bpm while galloping
  • 240 bpm maximum

Heart Size

It is a well-known fact that a horse’s heart is quite large. On average, a horse’s heart weighs approximately 1% of the body weight.

For instance, a 1000- pound horse would have a 10 lbs heart. The accurate heart weight may vary depending on the breed, health, fitness, and other factors.

The largest measured horse heart belongs to the legendary Thoroughbred racehorse Secretariat. It was not actually weighed during the “cosmetic” autopsy, the veterinarians tell that it was one of the largest they had ever seen. As per the equine historians and experts, it weighed approximately 21 pounds. 

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Fun Facts About Horse Heart

  • Like humans, horses can have a heart attack too, however, it is rare. 
  • The equine heart is quite similar to that of a human’s, only bigger. 
  • At, rest, a horse’s heart beats about 20 to 40 times.
  • One of the largest equine hearts belongs to the Secretariat.

Horses are amazing athletes and have only one large heart. The heart size and function are in accordance with the animal’s prowess. Their heart works in relation to their ability to move at high speed and endurance. 


Hi, I am Waqar and active in the horse world since 2012. I have MSc (Hons) in Agriculture from the University of Agriculture Faisalabad. I love to solve equine health care issues and note down in the form of research papers. I have written hundreds of equine health care, accessories, names, and history-related blogs. My equine related work is watering a lot of horse-related magazines and blogs.

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