Contracted
Heels: Cause for Concern
Could
your horse be predisposed to this crippling condition?
By
Adam Whitehead
Resident Farrier – UFVMC
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Contracted heels are found throughout all breeds of horses
and can affect horses from any discipline at any age. The
contraction is generally secondary to a variety of ailments.
Navicular disease, caudal foot pain, laminitis, club feet,
tendon contractions, conformational abnormalities, and injuries
to the affected limb are some of the underlying ailments that
predispose to or cause contracted heels. Any series of events
that result in inadequate weight bearing on the caudal aspect
of the digit and failure to properly load the digital cushion
can result in a contraction of the horses’ heels.
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Foot
Function
To understand why the contraction occurs, we must first understand
the functional anatomy of the caudal aspect of the foot and
the role it plays in the horses stride. The digital cushion
is an elastic network of collagen, fibrous tissue, and blood
vessels that lie between the Deep Digital Flexor Tendon (DDFT)
and frog, extending from the bulbs of the foot to just in
front of the point where the DDFT attaches to PIII and extending
outward to the lateral cartilages. The primary function of
the digital cushion is thought to be dissipation of the energy
from the ground reaction force. As the bare foot strikes the
ground in a normal heel first fashion, the heel, frog, bars,
and sole are loaded. The digital cushion is compressed and
the foot is expanded. This loading transfers energy and concussion
through these structures to the digital cushion. The energy
is then dissipated up the limb through hemodynamic transfer
(movement of blood), as the digital cushion is compressed
and the blood flows out and up the limb. Once the weight bearing
is removed from the limb, the digital cushion returns to its
static shape and negative pressure enables refilling of the
vasculature before reloading. This continual loading maintains
a healthy foot of normal size and shape.
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This
horse is suffering from contracted heels. Notice the atrophy
of the horse’s frog. |
Shock Absorbers
Once an ailment is present that changes normal weight bearing
on the limb and/or discourages a normal heel first landing,
the digital cushion is no longer loaded properly, therefore
reducing it ability to dissipate concussion. The concussion
of the ground reaction force is not effectively absorbed and
dissipated by the digital cushion and the boney column is forced
to then absorb the shock of the landing. This amplified concussion
has the potential, over time, to produce the degenerative changes
associated with Navicular Disease and other ailments of the
foot. Also, the elastic network of collagen and fibrous tissue
of the digital cushion are not fully expanded each time the
limb is loaded, causing them to atrophy over time. Once this
atrophy occurs, the heels begin to contract and lengthen, further
reducing the ability of the digital cushion to function. The
result is a foot that functions poorly and is much more upright
with heels that are contracted. |
Diagnosis & Treatment
A specific diagnosis should always be the foundation for treatment.
A veterinarian can perform a lameness exam as well as a variety
of diagnostic procedures such as radiographs, nuclear scintigraphy,
ultrasonography, CT and MRI. Once a diagnosis has been made
treatments can vary greatly. Most treatments should be aimed
at restoring normal weight bearing and alignment of the boney
column. Encouraging proper foot function and reducing the mechanical
stresses on the affected area are also of equal importance.
This is accomplished by first balancing the foot using the aid
of radiographs and/or structural markers of the foot and secondly
by moving the break over (the point when the heels lift and
the foot begins to leave the ground) closer to the center of
articulation. Heel elevation as well as incorporating a cushion
material in the solar surface of the foot can be beneficial.
No universal method is effective for all ailments; however a
farrier with a working knowledge of the functional anatomy of
the distal limb and an understanding of the diagnosis should
be able to offer a broad range of shoeing treatments. By combining
the work of a veterinarian and farrier a successful outcome
is generally achieved. |
Corrective
treatment begins with balancing the horses hoof and encouraging
proper foot function.
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References
Mike
W. Ross, Sue J. Dyson: Diagnosis and Management of Lameness
in the Horse, 2003, Saunders.
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Adam
Whitehead is the resident farrier at the University
of Florida Veterinary Medical Center. Whitehead completed
farrier school in Tennessee and studied animal science
at Abraham Baldwin Agriculture College in Tifton, Ga.
Prior to joining the UF team, Whitehead successfully
practiced in the field for 10 years.
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