Basic Hoof Anatomy Part 1: External Structures

Basic Hoof Anatomy Part 1: External Structures

Let’s start with the largest part of the bottom of the hoof. The sole of the hoof is the large, smooth area on the bottom of the hoof, depicted here in yellow. The sole includes everything between the white line and the bars. The white line, bars, and frog are not considered to be part of the sole. The primary function of the sole is to protect the sensitive internal structures of the hoof. The outer rim of the sole around the toe has an additional purpose, helping support the horse along with the hoof wall. 

The white line is a misleading misnomer, being more yellow than white and being located next to the inner wall which actually is white. In an effort to avoid this confusion, the white line is occasionally referred to as the “golden line” which was a commonly used term for the structure in the 1800s. The function of the white line is to connect the sole and inner wall of the hoof, protecting the pedal bone from bacterial infection. The white line creates a shallow groove around the outside of the bottom of the hoof. This groove fills with dirt which adds additional traction for the horse, allowing him or her to be more surefooted. 


Next to the white line is the inner wall. The inner wall differs from the outer wall in a few ways. The inner wall lacks pigment, leaving it white. The inner wall also has a higher moisture content, allowing it to be more elastic which protects the interior structures of the hoof from excessive shock. The inner wall’s elasticity also allows the pedal bone and outer wall to move in different ways without weakening the attachment. 


The hard, pigmented outer wall of the hoof carries the most obvious function of the hoof, bearing the weight of the horse. The outer wall also functions as a shell, protecting the inner structures of the hoof from harm. The outer wall acts rather like a spring during motion, storing and releasing energy during different phases of the horse’s stride. A healthy outer wall if free of cracks and growth rings. When healthy, the outer wall of the hoof is slightly thicker at the toe. The outer wall is nearly impermeable, again when healthy. Without cracks or damage, the outer wall keeps dirt, water, and any other substances from the outside world out of the hoof. Unfortunately, with hoof injuries or nutritional imbalance, the outer wall can weaken, allowing outside substances to penetrate and wreak havoc on the inside of the hoof.


The bar, which can be found alongside the frog, starts from the hoof wall and continues to about the middle of the length of the frog. While there is new research to suggest that the bars produce some of the material that forms the sole, the main purpose of the bars is to control the movement of the back of the hoof. The bars add strength to the heel area by preventing excess distortion. Because its job requires a lot of movement management, the bars should have a high ratio of pliable inner wall. 


The angle of the bar (or wall) is commonly referred to as the heel, though this can be misleading as it is a separate structure from the heel bulb. The angle of the bar is designed to take the main impact of the horse’s stride as it should land first when the hoof touches the ground. In order to absorb and dispel the excess shock of impact, the angle of the bar must primarily consist of pliable inner wall. This area also plays a large role in supporting the horse so it is vital for it to remain balanced. 


The collateral groove is the “V” shaped canal that runs along both sides of the frog. One side of the collateral groove is made by the walls of the bar and sole, the other is formed by the wall of the frog. This area should be inspected and cleaned out at least daily, though it is best to pick feet before and after turnout, as well as before and after work/riding. You can estimate the sole depth of a horse by measuring from the bottom of the collateral groove vertically to the height of the sole-hoof wall junction. 


The frog is one of the most important structures of the hoof. A healthy frog is wide, thick, and leathery. Frog health is exceptionally important for keeping a horse comfortable and sound. The frog allows a horse to move smoothly and effectively on uneven ground. The frog absorbs shock, facilitates circulation in the hoof, helps protect sensitive inner structures, and allows the horse to feel what’s under his hooves. The center of the frog sports a groove, called the central sulcus, which should be wide and shallow. If the frog is weak and narrow, the central sulcus can become deep and narrow, a perfect breeding ground for bacteria and fungus.


The coronet band, also sometimes called the coronary band, is a vascular structure at the top of the hoof wall, where the hoof attaches to the leg. The coronet band is very tough and has 2 prime functions; it produces the tubules that form the outer hoof wall and supports the internal hoof structures during movement. 

The final external hoof structure is the periople, a protective covering for the newly formed hoof wall produced by the coronet band. This new hoof wall, sometimes called the horn, is quite soft which prevents the coronet band from being bruised from the shock that transfers upward through the hoof wall when the horse takes a step. 

 

Thanks to the following sources for contributing knowledge. Please follow these links for more infrmation:

Premier Equine Ambulatory Veterinary Services: https://www.premierequinevetservice.com/know-your-horses-foot-anatomy/

The Equine Podiatry Association: https://www.epauk.org/about-equine-podiatry/articles/hoof-anatomy-a-beginners-guide/?doing_wp_cron=1631192771.7243969440460205078125

Horse Health Products:https://www.horsehealthproducts.com/horsemans-report/hoof-leg-care/hoof-anatomy

Dr. Barbara Parks: https://www.drbarbaraparks.com/blog/getting-in-touch-with-the-sole-of-the-horse

Progressive Hoofcare: https://www.progressivehoofcare.co.uk/guide-to-the-horses-foot.html

University of Missouri Extension: https://extension.missouri.edu/publications/g2740

Special thanks to Lindsay Bavone for providing the original picture of the underside of the hoof.




Leave a comment


Also in Articles

Getting Started in Hoof Trimming
Getting Started in Hoof Trimming

Continue Reading

Summer Hoof Care
Summer Hoof Care

Summer is finally on its way, bringing nice weather and horsey adventures. With fun summer plans in the works, we all want to make sure our horses stay happy and healthy through the good-weather months. While we can't bubble wrap your horse for you, we have a few tips to help you keep your horse's hooves healthy this summer.

Continue Reading

Eclipse Horseshoes
Eclipse Horseshoes

Hoof Trimmer Supply is proud to carry the innovative new Eclipse horseshoes that can either be glued or nailed on. Series I is a heart bar while Series II is the traditional open shoe.

Continue Reading