The importance of proper hoof care can not be overemphasized. To correctly trim and shoe a horse is a difficult task, both physically and
conceptually. Feet vary from horse to horse, and often from foot to foot on any given animal. Some horses are built straight and true and can be
fit into the standard rules and guidelines of farriery, but most are not. Therein lies the art of the job. Most horse owners entrust trimming or
shoeing to a skilled farrier although some owners with these skills and a strong back do their own shoeing or trimming. In either event, there are
basic principles that we should all be familiar with. At the very least knowledge of basic anatomy of the foot, use of proper terminology and an
understanding of the geometry of a properly trimmed foot will lead to a more open communication between owner and farrier.
The
foot is considered to be the hoof and all structures enclosed within the hoof capsule. In the next diagram we can see that this
includes many components, which emphasizes the impact on the horse of proper hoof trimming. Bones, tendons, ligaments, nerves, and
blood vessels are all enclosed within the hoof capsule.
The goal of trimming the hoof is to achieve
balance. With feet that are significantly out of balance, several shoeing or trimming cycles may be
needed to safely correct the problems. Also there are some horses with abnormal physical conformation that will not fit into the guidelines below.
Soundness is the goal, not necessarily a text book foot. The farrier shapes the hoof so that when it lands the impact is absorbed as effectively as
possible. This is generally achieved when four parameters are met.
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First, the bearing surface of the hoof should be symmetrical. The diagram below shows the bottom of the hoof after a trim where the foot is equally
balanced when a line is drawn from heels to toe through the middle of the frog.
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Second, when looking front to back (dorsal to palmar or plantar), the coronary band should be parallel to the ground surface and perpendicular to the
centerline of the pastern with the horse standing squarely.
In the picture below, the coronary band is not level with the ground and the walls of the hoof are of uneven length. Also notice the flare on the
inside wall.
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Third, the angle of the hoof wall and the angle of the pastern should be the same.
The next diagram shows good alignment of the dorsal hoof wall (B) with the coffin bone and the bones of the pastern compared to (A), broken back or (C)
broken forward misalignment. A broken back angle increases force on the structures in the back of the foot, promotes abnormal toe first landing and puts
excess strain on the deep digital flexor tendon. Both of the above conditions make the hoof wall more likely to develop cracks that can potentially be
debilitating. A broken forward angle can cause suspensory ligament strain, exaggerated heel-first landing and associated sole bruising.
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Fourth, the ground surface of the heels should be at or near the widest part of the frog when the foot is properly pared and shaped.
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Fifth, the breakover point must be correct. Breakover is the phase of the stride between the time the heel lifts off the ground and the time the toe
lifts off the ground. Breakover Point is the most forward place on the hoof or shoe that is in contact with the ground at the moment the heels rise off
the ground.
Looking at the diagram below, one can see that the length of the toe will change the length of the lever arm about which the foot rotates. It is also
known that increased tension on the deep flexor tendon from a long toe causes damage to the lamina of the hoof. Additionally there is more force placed
on the structures in the heel area from this increased tension.
To avoid these problems the foot must be trimmed and shod to create a correct breakover point.
The variables in achieving proper breakover are as discussed earlier:
- Correct hoof wall-pastern axis where the dorsal (front) surface of the hoof wall aligns with the bones of the pastern.
- Trimming the heels to be at or near the widest portion of the frog.
- Trimming the toe so that the breakover point is approximately 1” in front of the apex of the frog in the average (shoe size 0-1) normal, properly trimmed foot.
Breakover point can be manipulated in the barefoot horse by beveling the toe if needed to move the point backwards towards the heel. In the shod horse
one can use a squared or rolled toe on the shoe. The Natural Balance shoe is also a very effective way of managing breakover point.
A final check is accomplished by looking again from the side of the horse, (see below).
A normal foot properly trimmed will have the caudal (back) most aspect of the heel sit directly under a line drawn through the middle of the cannon bone
with the horse standing square.
A, shows correct alignment
B, shows short shoeing placing the foot too far foreword
C, shows how extending the branches of the shoe caudally corrects B
The shoe (left) is not wide enough or long enough. The heels of the foot are under-run and a crack is starting at the heel.
The rings visible on the hoof wall are from stress of abnormal forces from poor shoeing technique. The hoof (right) is severely overgrown,
the shoe is much too small and lacks caudal extension to support the heel area.
By looking at your horse’s feet before trim, you should be able to determine what needs to be accomplished at the farrier visit. Then re-examine
the feet after the work is done to see if your expectations have been met. Most horses do not need special trimming or shoeing and adherence to the
above basic principles can help to ensure healthy, sound feet. Discuss your observations and questions with your farrier to your satisfaction. It
will continue your learning experience.
If unresolved questions remain regarding the feet, especially if lameness exists, discuss this with your veterinarian, who after an exam may suggest
x-rays to further understand what is going on inside the hoof capsule. Among other things, radiographs can show the thickness of the sole, alignment
of the coffin bone with the dorsal hoof wall, alignment of the coffin bone with the solar surface and correct positioning of the shoe if shod.
Farriers often will request this and solutions are best accomplished with a partnership approach.
Long toe/low heel complex:
Some horses are naturally conformed this way, but more commonly this problem results from inappropriate hoof trimming.
If the heels are cut too short and the toe is left long due to poor technique, over time the situation becomes almost irreversible. It is especially
complicated if the shoes are not replaced on an appropriately short schedule
(six weeks in most cases). As time passes the heels of the hoof will overgrow
the shoe and will be crushed. At the same time the toe of the hoof is protected by the shoe and will continue to grow as it pulls the shoe foreword. This
usually causes the hoof wall tubules at the heels to angle foreword making them weaker to ground pressure and promoting collapse. The result is increased
pressure to the interior structures of the foot, a painful and damaging situation. Correction is difficult and involves actually shortening the heels to get
to normally angulated hoof tubules and regaining correct hoof angle by shortening the toe, backing up breakover and often using a wedged pad. Natural Balance
shoes are very helpful to achieve these changes.
Dished toe and/or flared hoof walls: This condition may arise due to an inherent abnormalities in the way a horse grows or uses the limb. If left
unattended, however the condition worsens, cracks often develop and hoof wall
breaks out. Correction involves rasping the flare or dished hoof wall
area to a normal shape, and in some cases applying a shoe. When shod, the shoe must be placed where it ought to go, not to where the flare or dish
extends to.
This foot was severely neglected. The toe is dished and the flare on the outside of the hoof broke out a large piece of hoof wall that was removed.
The foot was then trimmed and shod with a bar shoe.
Toes too long, heels too far forward: This is the result of incorrect trimming and results in the foot being placed too far foreword relative to
the line of force down through the cannon bone. When the foot is trimmed, in most cases, the bearing surface of the heels should be as far back as
the widest part of the frog.
In the diagram and picture below, the heels are too far forward:
In this diagram and picture the heels have been trimmed as far as possible at this time to the widest aspect of the frog:
Shoes fit too small: After trimming, the shoe is shaped to the foot. From the toe through the quarters, usually the shoe should follow the contour
of the newly trimmed foot. From the quarters back, however the shoe must be left wider to extend past the outside of the hoof wall by about the
thickness of a dime. This will allow room for the hoof wall to remain on the branches of the shoe as the toe grows forward and pulls the shoe with it.
The branches of the shoe should also extend slightly past the heel of the foot for the same reason.
This foot is long overdue for shoeing. Toe growth has taken the shoe forward leaving the heels exposed and the branches of the shoe inside the hoof wall
putting direct pressure on the sole.
Too many nails too far back: In general, the shoe can be adequately kept in place with 3 or 4 nails on the outside of the foot and 3 on the inside.
In any event, there should never be nails placed further back than the widest part of the hoof wall. Nails placed too far back restrict hoof wall
expansion.
Sore feet when shoes are pulled for winter: After 6 months of being shod the sole has gotten used to the protection of a shoe. When the shoe is removed
an adjustment period is needed for the sole to toughen up. If the horse naturally has a good thick sole, this adjustment may be little or none. For many
horses we recommend the following procedures, especially if soreness has been previously experienced:
Have the shoes removed without any sole being pared out. Remove only frog tissue that is overlapping or otherwise redundant. Shape the outer hoof
wall and any flares or dish conservatively removing only enough to smooth the edges and 45 degree the edge.
Have protective rubber boots on hand to use for a few days, or as needed. Bute may be needed for a few days and can be used after consultation with your
veterinarian. Plan on repeating a trim or rasping about two weeks after the shoes have been removed.
Secret to keeping healthy feet: There is no secret. Good quality feed; trace minerals daily, white salt block, and room to exercise on pasture.
- About 10 - 15 mm ( 3/8” to 5/8’) is a minimum sole depth to allow comfort barefoot for most horses.
- Most horses should be trimmed/shod at 6 week intervals to prevent overgrowth.
- The hoof wall grows downward from the coronary band and completes a new hoof in 9 to12 months.
- Toe length is about:
- 3” for 800 -900# horse
- 3.25” for 950 – 1050
- 3.50” for 1150 – 1250
- Front feet are rounder in shape and hind feet are usually smaller and more oval shaped
- There is no consistent scientific fact to support the use of “Hoof Supplements”. Same can be said for hoof dressings.
- White hooves are structurally identical to dark hooves. Common belief that white hooves are weaker may come from the ability to see bruises
easily through the lighter colored horn. Microscopic and tensile strength studies have proved otherwise.
- Thickness and durability of hooves vary widely with individuals, enabling some horses to go barefoot while others struggle without shoes.
Line drawings shown in this article taken with thanks from Adams' Lameness in Horses, Ted S.Stashak, ed., and New Hope for Soundness, Gene Ovnicek.
Thanks also to our farrier, Greg Wells for his consultation and contribution of some pictures to this article.
