|Esco Buff's Professional Farrier Service, LLC
In order to correctly construct and fit heart bar shoes, good quality and correctly taken radiographs will
need to be taken so the heart bar shoe will be able to be applied with accuracy and increase the chances
These few simple preliminaries will make the difference between a radiograph that has some use for
diagnostic and prognostic purposes and one which is not. In order for the Farrier to obtain the most
accurate measurements, radiographs should be taken within 48 hours of the Farriers shoeing visit.
A wooden block is needed about 2 1/2" to 3" high and wide enough for the horse to stand on. A cut off
metal rod is embedded into the top of the wooden block to highlight the ground line. The horse’s feet
should be brushed/cleaned out and the frog and sole should have any defoliation removed (photo 1).
The frog does not show up well on lateral/medial radiographs. In order to show the frog in relation to P-3,
a tack is used to highlight the frog. The tack is merely a reference point to determine proper placement
of the frog plate on the heart bar shoe. The tack is pushed into the frog. The exact placement is not as
important as long as its position on the frog is marked in some way. I prefer to place the tack at the widest
part of the hoof as measured from the white line. A heavy felt tip pen is ideal for marking the frog and
sole. The marked sole makes is more accurate to know the exact placement after the tack is removed
All radiograph images are subject to a magnification mechanism of minor or larger magnitude. This
means that all objects measured in a radiograph image will always appear larger on the image than in
reality (Sectra, 2009).
The magnification depends on both the distance between the focal point of the radiograph tube and the
image plate as well as the distance between the imaged object and the image plate. If the imaged object
is moved toward the focal point of the radiograph tube the magnification is increased and if the imaged
object is moved toward the image plate the magnification is reduced. Since all radiograph units are
different, they will all create different magnifications on radiograph images. A larger distance between the
focal point of the radiograph tube and the image plate reduces the effect of such movements (Sectra,
When acquiring a conventional radiograph image on which measurements of any type should be made, a
calibration marker should always be present in the image (Sectra, 2009).
To correct for magnification, a marker is used on the front of the hoof wall. A straight stiff wire of known
length (30 mm works best) is used to highlight the front and top of the hoof wall. A piece of copper or
steel wire works best. Do not use flexible or braided wire as this makes radiographic interpretation more
difficult. The length of the wire must be known so the effects of radiographic magnification can be
adjusted. The wire is taped to the hoof wall so the top of the wire is located where the wall changes from
hard to soft (Sectra, 2009; Eustace, 1996; Buff, 1990) (photo 3).
Proportionally using a 30 mm wire is helpful as the normal desired sole depth is 15 mm and the normal
horse hoof wall thickness is 15 - 17 mm; therefore should be about half the wire length on the radiograph.
Note - ponies normal hoof wall thickness is 13-15mm and Draft 19-21mm.
Also, for prognostic purposes, the wire marker is used on the front of the hoof wall. This information will
yield the founder distance, which is the most useful radiological prognostic indicator for acute founder
and sinker cases. This measurement will also help you monitor the horse’s progress.
The horse should ideally stand with one foot on each block with the cannon bone vertical. The
radiograph beam should be parallel to the top of the block and perpendicular to the axis of the limb so
that an absolutely lateral/medial radiograph is produced (photo 1).
Once the radiograph has been developed, the data can be collected by following the instructions on the
Founder Data Collection and Analysis Form Instruction Sheet ©.
© 2003 Esco Buff, PhD, APF, CF
Documentation Procedures (Can also be found in Esco Buff's Founder Book).
The following data is to be collected from the radiographs in order to be able to correctly construct and
apply a heart bar shoe (Buff, 1990) (photo 4 and 5).
The Founder Data Collection and Analysis Form© will aid in the collection of data (photo 4)..
The forms are clear and concise and include a laminated instruction sheet that enables the veterinarian
and farrier to more accurately assess, determine prognosis and establish treatment for the foundered
horse. The forms along with the Founder book will help the professional determine the chances that the
horse will return to its previous soundness state. The forms teach consistent radiograph techniques,
thus enabling the veterinarian and farrier to obtain more accurate information from the radiographs. They
also help determine where to correctly place the frog plate of the heart bar shoe.
Actual Wire Length - The actual wire length is the actual length of the dorsal wall wire marker used.
Radiographic Wire Length - This is the measured length of the dorsal wall wire marker from the
With the known actual wire length and the measured length of the wire from the radiograph, the
effects or radiographic magnification can be adjusted.
Magnification Correction - In order to get actual working measurements, calculations need to be made.
The magnification formula is actual wire length divided by radiographic wire length. For example, if an 50
mm wire is used and the wire measures 55 mm on the radiograph, then the magnification correction is
0.9 (50 ÷ 55). For any measurement taken from the radiograph, it will need to be multiplied by the
magnification correction in order to obtain the actual measurement. For example, if you take a
measurement of 45 mm on the radiograph, then you need to multiply that number by the magnification
correction, to get the actual length. In this example, 45 mm x 0.9 = 40.5 mm.
Wall Thickness - This is the distance from the wire marker on the dorsal hoof wall to the dorsal cortex of
the distal phalanx. This is to be measured half way up dorsally from the tip of the distal phalanx to the
base of the extensor process, and at a right angle to the dorsal cortex of the distal phalanx. Normal wall
thickness, uncorrected for magnification, has been shown to be 13-15 mm for miniatures, 15-17 mm for
horses, and 17-19 mm for drafts (Cripps and Eustace, 1999; Buff, 1990, 2005). Wall thickness will be
use to determine the Shoe Toe placement of the toe of the heart bar shoe.
This point is very important and quite often overlooked by many veterinarians and farriers. In the early
stages of founder, the hoof wall and the distal phalanx will draw apart and move downward, but remain
parallel. Rotation of the distal phalanx occurs later. By recognizing these early signs, the veterinarian and
farrier can provide immediate treatment that could help limit the amount of damage sustained.
Founder Distance - This is the vertical distance between the top of the dorsal hoof wall marker and the
proximal limit of the extensor process of the distal phalanx. Founder distance is the most useful
radiological prognostic indicator for acute founder and sinker cases. This measurement helps you
monitor the horse’s progress and along with type of founder (Laminitis, Acute, Chronic Type I, Sinker and
Chronic Type II), aids in helping estimate the prognosis and probability of return to soundness.
Palmar Cortex of the Distal Phalanx Length - This is the length of the palmar cortex of the distal phalanx
from the tip of the distal phalanx to the articulation of the distal phalanx and the navicular bone. It has
been shown that the wall thickness in the normal horse is approximately 25% of this measurement when
corrected for magnification (Pollitt, 2001). For example, if you take a measurement of 65 mm on the
radiograph, then you need to multiply that number by 25% (0.25) to get wall thickness. In this example, 65
mm x 0.25 = 16.25 mm. Remember, normal hoof wall thickness for horses is between 15 mm and 17
mm, uncorrected for magnification. In this case, the horse has a normal hoof wall thickness of 16.25.
This measurement will later be used to establish the correct placement of the toe of the heart bar shoe.
Shoe Toe Placement Calculation - This is the distance between the tack (which is merely a reference
point to determine the proper placement off the toe of the shoe), and a line drawn parallel to the dorsal
aspect of the distal phalanx, at the normal hoof wall thickness that was calculated from the Palmar cortex
of the distal phalanx length. In this case, 16.25 mm. The spot that this line intersects the bottom of the
hoof is the spot that the toe of the heart bar shoe will be placed at. This is the easiest and most accurate
method to determine the toe placement of the heart bar shoe. After taking this measurement, correct for
magnification and transfer this measurement to the foot. After the shoe is applied, the distorted hoof will
then be removed, exposing the dead laminar wedge.
Frog Plate Placement Calculation - This is the distance between the tack (which is merely a reference
point to determine the proper placement of the frog plate), and a line drawn perpendicular to the ground,
immediately behind the extensor process and bisecting the coffin joint space. This is the easiest and
most accurate way to calculate this measurement. This is the reason why correct radiographs need to be
taken and utilized for the shoeing treatment of any laminitic horse that heart bar shoes will be applied to.
After taking this measurement, correct for magnification and transfer this measurement to the foot.
A second method for determining frog plate placement is to measure the length of the solar margin of the
distal phalanx and then measure back 37% from the tip of the distal phalanx (Chapman and Platt, 1984;
Chapman, 1998; Butler and Platt, 2001). This method doesn’t work well when the distal phalanx is
Other data collected and documented on the Founder Data Collection and Analysis Form© are:
Founder Type (Laminitis, Acute, Chronic Type I, Chronic Type II, Sinker)
Dorsal Wall Angle
Distal Phalanx Angle
Solar Border Angle
Angle of Hoof Capsule Rotation
Angle of Distal Phalanx Rotation
As well as......
Breed of Horse
Gender of Horse
Age of Horse
Date Radiograph Taken
Date Data Collected
Which Limb is Radiograph of