Horse Anatomy: How Many Ribs Does a Horse Have?

Do you know how many ribs does a horse have? How much do you know about your horse’s anatomy? Unless you’re a vet or a veterinary student or an equine artist or student of equine art, the answer is probably not much! This is completely normal, but it can be helpful to you and your horse to learn a little!

A large part of the horse’s anatomy is its skeleton; the horse’s skeleton is extremely unique in comparison to all other animals. A piece of this unique skeletal structure is the horse’s ribcage.  A horse’s ribcage has a large impact on a horse’s appearance and built.

In this article, I will be discussing the horse’s rib structure and answering the question, how many ribs does a horse have? The equine rib cage is a very unique piece of anatomy, and much can be learned from it to better yourself as a horseman!

How Many Ribs Does a Horse Have?
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The simple answer to this question is that horses have eighteen pairs of ribs; eighteen on each side of their body for thirty-six total.  But, this can vary! It is not uncommon for horses to be born with an extra pair of ribs, making the count nineteen pairs, and thirty-eight total.

It is also common for a horse to have only one extra rib on either the right or left side, not a full extra pair.  This would make the count thirty-seven total, with eighteen on one side and nineteen on the other side.

How Many Ribs Does a Horse Have?

Horse Rib Shape and Structure

A horse’s ribs can be broken up into two major anatomical sections.  First, are the “true ribs;” these ribs are the first eight pairs of ribs in a horse’s ribcage.  When you can “see a horse’s ribs,” these are the ribs you are seeing. These ribs join pieces of the sternum or breastbone.

The second part of a horse’s ribcage, containing the last 10 (or more) pairs, is called the “floating ribs.” These ribs overlap and attach to each other.  These ribs are located furthest away from the horse’s head and are the shortest of the ribs.

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The longest ribs in a horse’s ribcage are the seventh and eighth ribs; these ribs are located in the middle area of a horse’s barrel.  The ribs get shorter as they progress toward a horse’s haunches.

Each one of a horse’s ribs are attached to a corresponding thoracic vertebra.  Thus, when a horse does have a nineteenth pair of ribs or even just an extra one, they are often misshapen or deformed.  The space between a horse’s ribs is called the “intercostal” space.

Rib Structure Importance in Equine Wellness

Ribs can play a significant role in determining and structuring a horse’s wellbeing.  In the 1970s, Dr. Don Henneke out of Texas A&M University developed a body scoring system that gauged a horse’s wellness and health off how visible a horse’s ribs were.

This system is still used today, and many horse owners and veterinarians use the visibility of and visible count of a horse’s ribs as an indication of that horse’s health and condition of wellbeing.

Owners give their horse a numeric ranking, depending on how visible (or not) its ribs are, and over the course of time reevaluate and re-rank the horse.  This is a good system to use when trying out new feeds, new supplements, or even a new turnout schedule to try to observe and record the ways in which your horse’s body changes.

A horse’s ribcage is also important to consider when fitting a horse for a saddle. When a properly fitting saddle sits on a horse’s back, it is primarily supported by the horse’s ribcage and the muscles that go over it.

Structure is Importance for Horse Health

The saddle’s width, in English riding, referred to as “tree” width, has to do with the width of the horse’s ribcage.  Get a saddle that’s too narrow, and you risk pinching the horse’s withers and ribcage, and get a saddle that’s too wide, and you risk the saddle sliding back across a horse’s barrel. 

A horse’s ribs also affect where the girth (English) or cinch (Western) sits.  Naturally, the girth will slide to wherever the horse is the most narrow.  Considering a horse’s barrel where it starts behind the front legs, to where it ends before the hind legs, the design of saddles is very logical.

The girth must sit behind the front legs because that is where the horse is the most narrow.  This shape, of course, is due to the shape, size, and structure of a horse’s ribcage. 

 If a horse is abnormally shaped, sometimes the ribcage gradually slants upwards toward a horse’s hind legs.  These horses may require a specially fitted girth or a breastplate in order to hold the saddle in place.

Read more about 15 Main Parts Of A Horse Explained.

Horse Ribs Compared to Other Animals

The primary difference between a horse’s rib cage compared to rib cages of other animals is count!  Humans only have twelve ribs, while other animals such as cows, sheep, cats, goats, and dogs have thirteen.  Animals such as pigs have thirteen.

Many believe that the horse’s long ribcage is what drew many early humans to try to ride horses opposed to other animals.  

Horse Ribs Compared to Other Animals

Conclusion

Horses have a very unique rib cage, consisting of thirty-six to thirty-eight ribs, eighteen to nineteen pairs! A horse’s ribs play a large role in overall wellness and saddle fit, as well as providing owners and vets with a good tool to analyze and compare a horse over periods of time.

A horse’s ribcage is completely unique compared to that of humans and those of other animals.  It is one of the reasons the horse is a desirable animal for riding, allowing the horse to be able to carry large things on its back such as saddles and people.

I hope this article helped you develop a better understanding of a horse’s anatomical structure by teaching you about the equine rib cage! If so, please share this article and share with us any relevant experiences and stories you may have!


FAQs

What are false ribs in horses?

False ribs, also called false vertebrae or non-thoracic ribs in horse anatomy, are short and stubby. These bones grow from the horse's body wall. They curve sharply outwards at their ends to attach to the ribs above them. Unlike true horse ribs which join with cartilage to horse's spine, false ribs have no connection to horse's spine (i.e. false ribs are not part of horse's rib cage).
The horse's false ribs are composed of 3 parts. They have a body or shaft, which is attached to horse’s body wall via tendons. They also have an angled end which curves outwards, away from horse's body wall. This angled end attaches to horse’s true rib above it via tendon. The third part is a tubercle, a small spur, which is located on horse’s body wall. This tubercle is where horse's false ribs connect to the vertebrae.
Horses normally have 10 pairs of false ribs on each side.
The horse's first two false ribs have a different shape from other false ribs. They are called floating ribs, or vertebrochondral ribs because they connect to horse’s vertebrae as well as horse’s rib cage.

What do false ribs do in horses?

False ribs play a crucial role in horse's mobility because they function as a lever for the horse's diaphragm. This allows horse to breathe more deeply and efficiently, which is important during run or galloping.
False ribs also protect the horse’s abdominal organs. They act like a shield during galloping. When horse kicks its hind legs, horse’s false ribs pull the intestines out of harm's way.

How does horse's false ribs function as a lever for horse’s diaphragm?

Horse’s breathing is done via horse’s diaphragm, which is a muscle that helps horse breathe. The horse's false ribs are connected to the vertebrae and then attach from there to the diaphragm. When horse inhales, horse’s false ribs raise and pull upward on the diaphragm.
False ribs function as a lever by magnifying the force applied to horse's diaphragm when the horse breathes in. This is why horse's false ribs need to be curved outwards. If they were instead straight and horizontal, the diaphragm would not lift as much when horse inhaled.
The first pair of false ribs (the floating or vertebrochondral ribs) play an even more critical role in horse's diaphragm. These false ribs are longer and pointier than other false ribs, which allow the first pair of false ribs to exert even more upward force on the diaphragm when horse inhales. This is the reason why horse cannot breathe efficiently without its floating ribs.

What are floating ribs?

The horse's floating ribs are a unique feature that distinguishes horses from all other mammals. Floating ribs are the first 2 pairs of false ribs. The floating ribs are attached to horse’s vertebrae via a special floating rib bone called the floating rib tuberosity, which is part of the floating rib.
The floating rib also connects to horse's diaphragm at another point besides its angled end which attaches to the true rib above it via tendon.
The floating rib tuberosity is located at the end of the floating ribs (where it connects to horse’s vertebrae). This floating rib structure consists of cartilage, not bone. It provides a flexible connection between floating ribs and horse's spine. The floating rib tuberosity is an important structure that allows floating ribs to move with the fluid motion of horse's spine as it runs.
The floating rib tuberosity also helps prevent floating ribs from fracturing by providing a flexible attachment point, which absorbs energy from impact during trauma so bones do not shatter.