The Geometry of the Hoof and the Hoof Print Trim

Published in Saddle Up Magazine in two parts, April 2015 and May 2015

           Nature seems to have a way when it comes to getting things right. The mathematical simplicity that exists when you break a hoof down into sections is quite amazing. At the Okanagan School of Natural Hoof Care we teach a trimming method called the Hoof Print Trim. This method was created by Cheryl Henderson, founder of the Oregon School of Natural Hoof Care. The Oregon School was the first of its kind in North America. A center devoted to the practice of Natural Hoof Care and a better life for our equines. Cheryl Henderson has spent many decades developing and researching her method and has proven it again and again with thousands of dissections and case studies. Our program teaches this method and also relies on the ability to “read” the hoof and each horse’s specific conformation to adapt the trim to their needs. This system allows us to teach the fundamentals of trimming in a short time frame.

The formula of a healthy hoof is as follows: the width at the fulcrum (widest point on the bottom of the hoof) equals the length heel to toe. This means that the hoof should be a perfect circle, hind hooves abide by this measurement also but the hoof tends to be more spade shaped. The frog should equal 2/3 of the solar view of the hoof from the back to the front, the remaining sole to the dorsal (front) hoof wall is the other 1/3. The hairline should be at a relaxed 30 degree angle to the ground. All hooved animals have a naturally occurring 30 degree hairline that only becomes distorted through genetic defect, altered living environments and lack of movement, or human trimming error. These formulas have been proven again and again through the study of wild horses’ hooves and as well through countless dissections and case studies. Even the most distorted hoof shapes follow these parameters and can often be brought back into balance in just a few trims depending on the severity of the distortion. This does not mean however that we just measure and cut. These guidelines must be paired with our “reading” of the hooves’ clues to help us determine each horses’ needs. For instance some horses have club feet, therefore this physical deformity will impact the heel height and the angle of the hairline. This is where reading the hoof and determining the best approach for each specific horse is extremely important. A deformity like club foot can sometimes be corrected or improved, but many times is just something you have to work with and adapt your trim around.

Showing the 2/3 to 1/3 balance of the hoof

            The Hoof Print Trim is a great starting point for those learning to trim because you can measure and draw where the healthy hoof should be and then train your eyes to “read” the hoof and evaluate using both sets of clues where you should trim. This method starts with evaluating the baseline. The baseline is the rearmost part of the hoof, where we will trim our heel height down to as well as where we take our measurement from heel to toe after establishing the width at the fulcrum. To find our baseline we measure from the back of the heel bulbs at the hairline to the collateral groove exit. On most average sized horses this measurement equals 1 ¼ inches. It varies for ponies or smaller horses and the taller horses and drafts but this is just an average, and again not a measurement we would simply just cut without “reading” into the rest of the hoof first and accounting for and deformities or pathologies etc.  After establishing the correct baseline by evaluating the frog health, the periople wear marks, the heel surface, and sole thickness in switchback at the rear of the hoof, we can measure our fulcrum to establish our toe length. 

Establishing the baseline

                The fulcrum is simply the widest part on the bottom of the hoof. It is almost always about ¾ inch behind the apex of the frog occurring at the mid-point of where the coffin bone sits inside the hoof and is not usually distorted by flaring or stretched lamina. We measure the fulcrum from the golden line on one side to the golden line on the other side, not from wall to wall. If the measurement was 4 ½ inches, we would then measure from our baseline forward 4 ½ inches and mark where our golden line should be at the toe. In a balanced hoof that has been trimmed regularly and correctly, this mark will line up with the golden line at the toe. I just want to reiterate that this is also not a cut line, we still have to add our wall thickness to determine where the cut line will be. We also must “read” the hooves’ wear patterns and toe callous before deciding where to cut. Now that we have determined the circumference of the hoof we can establish the 2/3 to 1/3 balance. The baseline to the apex of the frog should be 2/3 of the overall hoof length. Frogs can get stretched forward into the sole’s 1/3 and occasionally need to be trimmed back. This measurement will determine if the frog has migrated forward. However all of our measurements to this point would be inaccurate if we had measured our baseline wrong, so caution must be taken to measure correctly and confirm we are right by reading” the clues and wear marks in the hoof.

               After establishing the baseline and the heel height we must determine the length of the toe. We do not use the white line as a determining factor as it can stretch and migrate forward giving a false location for the toe length. In order to determine the proper length we measure the fulcrum width from white line to white line on either side of the hoof. A front hoof should be the same width as length. So if the fulcrum is 4 ½ inches from white line to white line then our measurement from the baseline at the rear of the hoof to the toe would be 4 ½ inches. This is not a cut line though, we still have to add the thickness of the hoof wall to this measurement. A lot of times in a run forward hoof the white line can stretch forward and this measurement can seem extreme. However even though the wall flares forward and the white line stretches, the internal structures do not move or migrate. The coffin bone can rotate and sink lower in the hoof capsule in a laminitic or foundered horse, but even in those cases the geometrical mapping will establish the location of the coffin bone before we start to trim and we can work to bring balance back to the hoof.

           Another factor we have to consider when aligning the bones of the hoof and lower limb is the hairline angle. All hooved animals in nature have a 30 degree hairline in their natural environment (barring rare genetic defects) and the horse is only an exception when trimmed and managed ineffectively. Studies of wild horses in the US Great Basin have shown that when allowed to naturally wear their hooves in their wild environment they almost always have a 30 degree hairline. The few horses with this exception have a genetic defect of a club foot. A club foot is a coffin bone with a steeper dorsal angle and therefore creates a hoof with a steeper dorsal hoof wall angle and a higher heel. Both of these pathologies will affect the hairline angle.

After evaluating the baseline, the fulcrum, the toe length and the hairline angle, we finish our trim by defining and trimming the bars and putting the mustang roll on the front of the hoof. The bars function is for support in the rear of the hoof and it is important that they are not over trimmed, however they must also not be left to grow over the sole as they can cause bruising and abscessing. A mustang roll is a rounding of the hoof wall at the toe to remove any leveraging forces on the hoof wall and to create a smoother breakover. The mustang roll is one of the defining differences between a barefoot trim and a traditional farrier trim.

On the left a natural trim with a mustang roll, on the right a traditional pasture trim.