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From many horse owners' point of view,
the farrier's profession throws out a lot of confusing
terms and directives when it comes to balancing a foot.
Fit the shoe full? Trim to the widest point of the frog?
Use a four-point trim? These nebulous statements can
place the horse owner in a precarious position, as
it seems like everyone has a different way
to describe what can or should be done to a horse's foot
during trimming and shoeing. |
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"Although
we as horse owners pay for a farrier's professional
service, it is advisable that we at the very least have
a basic understanding of what a well-shod horse is,' "
Dave Duckett stated at the 52nd Annual Convention of the
American Association of Equine Practitioners, held in
San Antonio, Texas. |
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Duckett, a Fellow of the Worshipful
Company of Farriers in London, England, and a member of
the International Horseshoeing Hall of Fame, developed a
system for evaluating hoof balance and shape more than
20 years ago (you might have heard of Duckett's Dot and
Duckett's Bridge), and his work fundamentally changed
how many farriers evaluated feet. He believes that
farriers, owners, and veterinarians need to have a
consistent, reproducible way to evaluate foot shape and
balance, and that his system gives us this. At the
convention, he presented a discussion of his system and
its implications for foot care during the
standing-room-only "Putting Science into Farriery"
session. |
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General
Thoughts on Hoof Care and Soundness |
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"Farriery is one of the most important
elements in general horse health care and maintenance in
preservation of the sound horse," Duckett began.
"Preservation of the sound horse is important, because
if we do preserve the soundness of our horses, we won't
get problems to fix later. |
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"Our
objectives are to maintain a comfortable, sound horse,
protect the foot and support the limb, accurately apply
treatment procedures to prevent and treat pathological
conditions, and enhance the horse's natural ability and
allow maximum potential development," he noted. |
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But how do
you know what care and trimming/shoeing a foot needs?
Duckett says it is imperative that we work in harmony
with the naturally designed hoof. "Moreover, knowledge
of the horse's anatomy, physiology and biomechanics
plays a crucial role in understanding good
horseshoeing," he commented. |
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Since not
everyone keeps a radiograph (X ray) machine in their
back pockets to see and understand the hoof's internal
structures, he used the fundamentals of these sciences
to map out external reference points on the hoof (Duckett's
Dot and Duckett's Bridge; more on these shortly) and
correlate them to the internal structures. In other
words, certain areas of the hoof correspond with certain
internal structures no matter how distorted a foot might
look. |
"Why do we need this system?" he asked
the audience. "Owners, farriers, and equine health care
practitioners need to be able to accurately appraise a
horse's foot. We all have a basic need for accurate hoof
evaluation, and a need to communicate using the same
terminology. Using this information (hoof shape and
balance relative to Duckett's Dot and Duckett's Bridge),
we can:
- "Discover the interval for
optimal shoeing (ideal time between shoeings).
- "Evaluate the correctness of
trimming and shoe placement. We need to know the
horse's anatomy before trimming and applying a shoe.
- "Make an accurate diagnosis to
arrive at the correct treatment measures.
- "Establish criteria for
biomechanical studies. There is a definite need for
a baseline (level of hoof balance) to work from and
criteria to understand what a well shod horse is,
before we do these studies. Having such a system
sets standards for inter-professional
communication."
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Duckett's Dot |
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"The
basic concept of using Duckett's Dot and Duckett's
Bridge is to measure the foot from the center to its
peripheral borders, rather than using traditional
methods of calibrating the exterior, which would
perpetuate the errors of the past (with distorted
feet)," Duckett explained. |
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So where
is the center of the foot, and how do you find it?
Duckett explained that the center of the foot is the
center of the third phalanx bone, which is often termed
the coffin bone. |
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"The
third phalanx is the physical, dynamic foundation of the
foot," he stated. "Therefore, knowing its position
within the confines of the hoof capsule is crucial. The
external landmark of the center of the third phalanx is
noted by Duckett's Dot. This is a consistent external
reference point situated 3/8" behind the apex of a
trimmed frog on the average-sized horse. This is
proportionate from the Shire to the Shetland (the point
is slightly further back from the apex on a Shire, and
slightly closer on a small Shetland). |
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"From the position of the Dot, the
third phalanx can be balanced by measurement and weight
mass," he went on, showing a photo of a coffin bone
balanced on the point of a pencil at the Dot to
illustrate its physical balance. |
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Using the
Dot |
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Optimal toe length
"Understanding that there's an equal amount of tissue
(wall) attached to the third phalanx bone, we can scribe
around the hoof wall to gain maximum toe length (with a
compass like the one we used to draw perfect circles in
school)," he said. "From the Dot to the medial wall,
scribe to the toe. This will assure maximum toe length
(anything outside that line means the toe is too long). |
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If the
horse's toe is very long, he advised a cautious
approach: "Radical reformation of the hoof capsule at
one time is not necessarily a good thing, it has to come
over time. You're only doing a little at a time, don't
overdo the job to emphasize the work. |
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"For the
working farrier, a better perspective on the foot's
internal structures can be gained when using these
external reference points," he said, noting that the
third phalanx on most horses toes in an average of four
degrees. |
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Dubbing the toes
"We don't have to rasp the toe off to conform with the
traditional type of shoeing," he commented. "If the hoof
wall is long, rasping it back to match an ideal is not
necessary. The foot is a conical (cone) shape, and its
strength is in its shape. If you rasp the toe back, you
are rasping away the cortex and strength of the foot. If
the foot loses that strength, it will collapse onto that
shoe, creating lameness. This has been witnessed by many
horse shoers attempting to create a short toe and in
following the 'natural craze.' " |
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Duckett's Bridge |
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The Bridge is a line rather than a point
like the Dot, and it lies behind the Dot. It is a
horizontal line running from medial (inside) to lateral
(outside) sides of the foot. The Bridge is directly
beneath the center of rotation of the distal
interphalangeal joint, also called the coffin joint.
Externally, you can see this as the widest part of the
foot, which corresponds to this horizontal line.
Therefore, the Bridge can be used to separate the foot
into halves. |
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"The anterior or cranial (front) half of
the foot includes tendon attachments on the third
phalanx for movement, among other things," he said.
"This half holds the bone and laminar attachments. The
caudal or rear half is made up primarily of softer,
elastic tissue. The separation of these occupations is
an area named the Duckett Bridge, which is also
considered to be the central biomechanical balance point
of the foot." |
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When the foot is properly balanced,
Duckett says, the bridge is exactly halfway between
breakover at the toe and the heel end of the shoe. And
if it's not, he noted that the heel bearing areas of the
foot will be under great stress, resulting in collapsed,
underrun heels. But the heels will collapse no further
forward than the bridge. |
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Shoe
Placement and Size |
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"When a horse is shod, he is no longer
standing on his feet--he's standing on his shoes,"
Duckett stated. "Therefore, it is imperative that the
shoe is placed with biomechanical congruency (to match
the biomechanical needs of the foot). The shoe should be
placed central to the Bridge (with equal ground surface
length in front of and behind the Bridge) and in harmony
with the horse's movement, regardless of the hoof
shape." |
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The distance between breakover (the
forwardmost point of the shoe's ground contact) and the
Bridge should equal the distance from the Bridge to the
heel end of shoe, he clarified. Breakover is not
centered on the toe, he added; as mentioned earlier,
most horses' bony columns toe in slightly. "The anatomy
and its mechanics determine where the breakover is," he
said. |
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Using this
technique also gives you a basis on which to evaluate an
existing shoeing job. Duckett gave case examples in his
presentation and challenged the audience to "raise their
conscious awareness to such a level that you see what
you are looking at. This may be a simple statement, but
it has a important meaning," he said. |
Using radiographs to complement the
information on a particular case, he noted: "If the
front half of the foot is for tendon attachments,
laminae, and bone, and the back half is for weight
bearing, how much shoe is there to support that limb
(i.e., how much shoe is there under the rear half of the
foot bearing the horse's weight)?
Just the little bits at the ends of the branches. It's
not nearly enough." |
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Take-Home
Message |
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"Think about what you've leaned today and
place it into practice when appraising a horseshoeing
job," he concluded. "Some schools of thought view the
art and science of farriery as merely covering the
preparation of a horse's foot and the application of a
shoe. But it's a little more than just slapping a shoe
on. We all must appreciate that the foot is the
foundation of the horse, and we must also become aware
that it's the art of horse shoeing, not FOOT
shoeing." |
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