Hoof School: Part X - Dorsal Angle, Hairline, Capsule Crease, and Airgap

October 30, 2017

This will be the last blog providing additional tools to evaluate your own horse’s hooves based on the blueprint provided by the internal structures.  We will now be moving from evaluating the bottom of the hoof to evaluating the outside of the hoof capsule.  We will start by going over the dorsal angle of the hoof capsule.


The front half of the hoof capsule should follow the shape and angle of the front of the coffin bone; this angle is known as the dorsal angle.  Once again, through years of research and thousands of dissections Cheryl has come up with averages for these angles.  For front hooves the dorsal angle of the coffin bone ranges between 45 to 50 degrees with an average of 47/48 degrees.  For hind hooves the dorsal angle ranges between 55 to 60 degrees with an average of 57/58 degrees.  Since we already know the hoof wall tubules are attached to the coffin bone through the laminae growing from the coffin bone, it makes perfect sense that the capsule wall formed by the wall tubules should follow the angle of the coffin bone in our ideal hoof capsule.


You can buy an inexpensive angle gauge from your local hardware store to measure the angles of your own horse’s dorsal angles.  When using the angle gauge make sure the horse is standing on level ground.




Next, we will learn to read the hairline as a clue to the balance of the hoof capsule.  When the hoof is balanced heel-to-toe and lateral-medial, the hairline forms 30 degree angle with the the ground based on the internal structures.  Lateral-Medial balance means both sides of the hoof capsule are equally covering the internal structures which ensures the internal structures are not damaged upon loading.  Cheryl’s book comes with an angle gauge which can be used to easily measure the hairline, but if you don’t have her book you can easily make your own.

 Click images below to enlarge:


Based on the natural shape of the internal structures there should be a slight airgap in the quarters.  You can test for airgap by trying to slide a business card under the hoof at the quarters while the horse is standing on a flat, solid surface.  If the card slides under, you have airgap...if not...you don’t!  Having airgap on both the medial and lateral side the hoof also provides additional confirmation that the hoof has lateral, medial balance.  Click images below to enlarge:


 The hairline can also be used as a clue for airgap.  In our ideal hoof capsule the hairline forms a straight line.  If you notice the hairline is not a straight line this means some of the wall tubules are too long which is causing them to push up against the hide skin which covers the upper outer area of the lateral cartilages.  If you follow the individual tubules from the area on the hairline that is bent towards diagonally down towards the ground it will show you the areas of the hoof wall that need additional trimming to relieve this pressure.  Image on left shows ideal, straight hairline and image on right shows a capsule with a bent hairline...click images to enlarge:


The last trick I will share with you is a quick and easy way to check the toe length of your horse’s hooves.  Through her research, Cheryl has determined that the average toe length of a standard horse is 3 - ¼”...which happens to be the same average length of a women’s middle finger or a man’s index finger....very convenient!  So for a quick and easy check to see if your horse’s toe length is too long, simply place the area where your finger (middle finger for women and index finger for men) meets your palm at the top of your horse’s hoof wall above the toe (front and center of the hoof).  If your horse’s toe ends at the tip of your finger this is confirmation that your horse’s toe length is near ideal, but if you notice the toe is substantially longer than your finger you may have just discovered your horse’s toe length is too long.  You can also use this method to quickly verify all of the toe lengths of your horse's hooves are the same.  Just like all of our other evaluation methods this is based on an average, so there will be some variation.  If you have very large horse you can expect the ideal toe length to be a bit longer and if you have a pony you can expect the ideal toe length to be shorter.



One additional clue the hoof provides for toe length is the capsule crease.  This is a stress crease which is caused by the force of excess toe length causing the wall tubules to bend (crease).  It wraps around the lower area of the hoof and generally forms at the ideal length of the toe, so if you notice this crease is at the same location as the measurement you made with your finger previously you have additional validation for your horse’s ideal toe length.  Click images below to enlarge:


 In review, the following are what we are looking for in our ideal hoof capsule when viewed from the outside:


  • Dorsal angle follows the angle of the coffin bone:

    • Front:  45 - 50 degrees (47/48 average)

    • Hind:  55 - 60 degrees (57/58 average)

  • Hairline is a straight  line and forms a 30 degree angle with the ground

  • Airgap is present in the quarters on both sides of the hoof

  • Toe length

    • approximately 3 - ¼” for standard horse (less for pony more for large horse)

    • Same length on all four hooves


Do your horse's hooves meet all of the above criteria?


Phew!...we covered quite a bit of material in this blog series!  I have one more conclusion blog which will get you thinking on why trimming is necessary in the first place and why poor trimming can lead to hoof pathologies in domesticated horses.  It will also provide you with a bit more information about what you can expect from the article I have in the works to be available for download from my website in November!




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