A simple rule of thumb, called “Duckett’s Dot,” helps farriers locate the internal structures of a hoof without the use of X-rays.
Shared first at the 1988 American Farrier’s Association Conference, Duckett’s Dot remains the most comprehensive, easy-to-follow system for evaluating the balance of the foot, something every horse owner should understand.
Dave Duckett, a British farrier now living in Pennsylvania, presented a system that was both incredibly simple and a stroke of genius. He emphasized that the foot is a three-dimensional structure and proper balancing must take into account the location of structures inside the hoof, explaining how the hoof can best be trimmed to allow those structures to function in the most mechanically efficient manner. The benefits include comfort, freedom of stride and prevention of lameness.
Duckett explains the foot has a center axis, a line that runs vertically directly through the center of the coffin bone and intersects P3 at the extensor process. The line also passes through the center of key nervous and arterial structures inside the foot. This line would exit the bottom of the foot at a point about 3/8 of an inch behind the point of the frog. That point is what has become known as Duckett’s Dot. The beauty of this system is that the dot will always be located at the same spot on any horse, whether a 500-pound pony or a 1,300-pound warmblood.
The distance from this center axis dot to the side of the hoof should be same on both inside and outside. This same measurement should equal the distance from Duckett’s Dot to the toe.
Each horse has his own ideal breakover point, which is dictated by his center axis and Duckett’s Dot. If the horse’s toe is too long, the Duckett’s Dot measurement will fall on a spot inside the hoof wall, white line or sole. If too short, Duckett’s Dot will fall outside the existing toe. If you line up the tip of the toe with Duckett’s Dot, it will automatically be the correct length for that horse.
Of course, there’s more to balancing the foot than this, and the Duckett system acknowledges that. Once the correct position for the toe has been established by Duckett’s Dot, a landmark called The Bridge comes into play. The Bridge, which is located behind Duckett’s Dot, is an imaginary line that travels directly below the center of rotation of P2 and directly below the junction of the navicular bone with P3.
The easiest way to pinpoint its location is to measure the length of the toe from the coronary band to the ground, after the foot has been trimmed so that the tip of the toe corresponds to the correct position predicted by Duckett’s Dot. You then measure from the tip of the toe on the bottom of the foot back for the same distance. This will give you the position of The Bridge.
The significance of The Bridge is that it should be the exact center of the hoof in an anterior-to-posterior direction. If you drop a line straight down from the bulbs of the heel to the ground and measure the distance from the tip of the toe to that spot, The Bridge should be directly in the middle of that line.
Duckett also believes the edge of the toe should be rolled to allow for easy breakover. (Horses eventually wear their own breakover points, even on shoes. If you look at a well-worn shoe, you will note the toe has become beveled/rounded at the point of his normal breakover.) To determine how much of the toe should be rolled, Duckett uses the dimples in the coronary band, located at the top of the natural toe pillars to either side of the extensor tendon.
The lateral-to-medial (side-to-side) balance of the foot can be checked readily using a dot system also. With the foot on the ground, a dot is placed/imagined in the center of the bulb of each heel. The distance to the ground from that dot should be the same on both sides.
With the foot now balanced, attention returns to The Bridge if a shoe is to be put on the horse. In this system, the front edge of the shoe is placed at the point of breakover for the rolled toe. The toe could be squared to match the toe or the weightbearing surface beveled at the breakover surface, as natural wear does to an initially flat shoe. The measurement is taken from the breakover point back to The Bridge. The length of shoe in front of and behind The Bridge should be the same. Since many horses are shod with too much toe and heels too far underneath, the heels of the shoe often extend somewhat beyond the horse’s anatomical heel and provide for better support.
The system also fits the shoe wide at the heel, typically by 1/8 inch, to broaden the base of support to a normal dimension and allow the heels to expand.
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