Anatomy: Equine

Spine & ribs

Equine Anatomy

Welcome to equine (Suwatâga) anatomy (Wîchasta Tachâ)! We will be going through some of the major body systems, such as the respiratory system, the digestive system, the cardiovascular system and the musculo-skeletal system. An interesting fact about horses is that they are able to rest while standing with little muscle activity. This process is called the passive stay apparatus, and allows horses to conserve energy.

The Respiratory System

Just like us, horses (Suwatâga) need to breathe oxygen in order to fuel their muscles (ka). The respiratory system includes the lungs (Charhu) and the path that air takes to get to the lungs. Horse lungs (Charhu) are massive! Human lungs can hold 1.5x more air than an empty milk jug, but a horse’s lungs can hold 14 milk jugs worth of air!  

Horses are obligate nasal breathers – they can’t breathe through their mouths. This is because the pathway between the mouth and the lungs is blocked off so that food doesn’t accidentally get brought into the lungs. 

Equine Skull

Equine Teeth (Hîthke)

What makes human teeth and horse teeth different? Horse teeth (Hîthke) grow continuously throughout their life. Human teeth stop growing once our permanent teeth come in. Horse teeth are naturally ground down by chewing rough, fibrous food (wonâpche) like hay.  Just like humans, horses can have teeth problems. Sometimes, horse teeth wear unevenly, and they can get sharp edges that can cut into their cheeks. Veterinarians fix this by “floating”. This is the process of manually grinding down the teeth that aren’t naturally grinding down from chewing. 

Equine Digestive System

Plants (Wouya) are made up of a structural molecule called fibre and animals are unable to digest fibre on their own. Herbivores, like horses, have to come up with a strategy to fix this! Horses are hindgut fermentors, this means that they use a digestive process where fiber is digested with the help of bacteria that live symbiotically in the animal’s cecum. 

Equine Stomach

Equine Stomach

A horse’s stomach (Tethi) is very unique. Your stomach, and even your dogs or cat’s stomach, are completely glandular. These glands secrete mucous, acid, and proteins that help breakdown food. A horse’s stomach has both glandular and non-glandular sections, which are separated by a band called the margo plicatus.  

Equine Ascending Colon and Cecum

They have a massive cecum and ascending colon (Sube) that contain bacteria that help breakdown the food that their stomach (Tethi) can’t. How massive is massive? The cecum and ascending colon house billions of bacteria and can fit between 90 to 135 liters of liquid - that’s equivalent to almost 34 jugs of milk!  

Equine Cecum & Ascending Colon Dorsal View
Equine Ascending Colon & Cecum

Equine Cardiovascular System

Horses (Suwatâga) have really big hearts! A horse’s heart (Châde) is 13 times bigger than an adult man’s heart. Horses are incredible athletes and they need to have a very strong heart (Châde) so that they can get oxygen and nutrients to their muscles (ka) while they are running.  

Equine Musculoskeletal System

In this video you learn about equine bones (Huhu) and muscles (Ka) ! You will also learn the difference between plantigrades, digitigrades, and unguligrades. Horses are what extreme unguligrades. As a result, their limbs are longer which allows them to take longer steps. They have also decreased the weight of their lower legs which reduces the cost of swinging the leg, making them highly effective at running!

Distal Limb

Equine Distal Limb

The bones (Huhu) in a horse’s distal leg (Cheja) have many different names. The common names of these bones (Huhu) are the cannon bone, the long pastern bone, the short pastern bone, and the coffin bone. On either side of the cannon bone are splint bones that are remnants of the other fingers that were present in the ancestors of the horse. Did you know that horses walk on the equivalent of a human’s middle finger? Over time, their five digits have been reduced to one single digit. 


Equine Distal Limb Joints

Joints (Huhu kokîheyabi) allow for movement between bones (Huhu). In the distal horse limb there are 3 joints: the distal interphalangeal joint, the proximal joint, and the metacarpophalangeal joint. These names are pretty complicated, so equine veterinarians generally use common names such as the fetlock joint, the pastern joint, and the coffin joint. Bones are also connected by ligaments, which are tough bands of tissue that hold the joints (Huhu kokîheyabi) and bones (Huhu) together.  

Hoof Wall

Equine Hoof Wall

A horse’s hoof (sagể) is equivalent to a human fingernail and is made up of a protein called keratin. Since horses are so heavy, their hooves are designed to decrease the impact of the force when their foot hits the ground.

Equine Hoof

Equine Hoof

A horse’s hoof (sagể) has multiple different parts. They have a wall, a sole, bulbs, and a frog. The bulbs and frog are equivalent to the skin (ha) of a human’s finger. So, if a horse’s hoof wall is like the fingernail (sage) in a human and the bulbs and frog is like the skin (ha), what do you think the horse is walking on? 


Which of the below diagrams shows the organs in the correct location?