Abstract and Figures

Objective: To monitor changes in hoof morphology in response to barefoot trimming. Methods: Seven horses were trimmed every 6 weeks according to barefoot trimming principles, which involved levelling the hoof to live sole, lowering the heels, bevelling the toe and rounding the peripheral wall, while leaving the sole, frog and bars intact. A 4-month period was allowed to lower the heels sufficiently to achieve a hoof shape representative of the barefoot trim. This was regarded as the starting point for morphological adaptations in response to maintenance of the trim. Hoof morphology was measured from lateral, dorsal and solar view photographs and lateromedial radiographs taken at 0, 4 and 16 months. Changes from 0 to 4 months represented differences between a natural hoof shape and the trim, while changes from 4 to 16 months represented adaptive effects during hoof growth. Results: Establishment of the barefoot trim involved significant shortening of the toe, heel and medial and lateral walls, with increases in angulation at the toe, medial and lateral walls, but not at the heel. Maintenance of the trim resulted in a palmar/plantar migration of the heels, with increases in support length, heel angle and solar angle of the distal phalanx (P3). Conclusions: Bevelling the toe and engaging the frog and bars in the weight-bearing function of the foot resulted in elevation of the heel angle and solar angle of P3. These changes may be beneficial in treating under-run heels and negative solar plane angulation of P3.
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Effects of barefoot trimming on hoof morphologyavj_806 305..311
HM Clayton,* S Gray, LJ Kaiser and RM Bowker
Objective To monitor changes in hoof morphology in response
to barefoot trimming.
Methods Seven horses were trimmed every 6 weeks according to
barefoot trimming principles, which involved levelling the hoof to
live sole, lowering the heels, bevelling the toe and rounding the
peripheral wall, while leaving the sole, frog and bars intact. A
4-month period was allowed to lower the heels sufficiently to
achieve a hoof shape representative of the barefoot trim. This was
regarded as the starting point for morphological adaptations in
response to maintenance of the trim. Hoof morphology was mea-
sured from lateral, dorsal and solar view photographs and latero-
medial radiographs taken at 0, 4 and 16 months. Changes from 0 to
4 months represented differences between a natural hoof shape
and the trim, while changes from 4 to 16 months represented adap-
tive effects during hoof growth.
Results Establishment of the barefoot trim involved significant
shortening of the toe, heel and medial and lateral walls, with
increases in angulation at the toe, medial and lateral walls, but not
at the heel. Maintenance of the trim resulted in a palmar/plantar
migration of the heels, with increases in support length, heel angle
and solar angle of the distal phalanx (P3).
Conclusions Bevelling the toe and engaging the frog and bars in
the weight-bearing function of the foot resulted in elevation of the
heel angle and solar angle of P3. These changes may be beneficial
in treating under-run heels and negative solar plane angulation of
P3.
Keywords barefoot trim; biomechanics; farriery; hoof angle;
horses; under-run heels
Abbreviation P3, distal phalanx
Aust Vet J 2011;89:305–311 doi: 10.1111/j.1751-0813.2011.00806.x
Protecting the foot of the domestic horse represents an impor-
tant husbandry practice, documented throughout history,1
that aims to maintain a relatively healthy foot and, hopefully,a
horse relatively free of severe or chronic lameness problems. These
methods included a wide range of devices from non-metallic materi-
als attached to the foot via straps or harness-like materials to metallic
objects resembling the horseshoe of today. While early Greek horse-
men preferred breeding methods to ensure healthy feet, for the last
several hundred years the metallic horse shoe has been a method of
choice.1Much research has been performed documenting the bio-
mechanical and physiological effects of shoeing on the foot under
static and dynamic conditions2–4 as well as the effects of different
ground surfaces.5,6 As a result, significant insights have been gained
regarding the effects of physical forces during foot-ground impact on
the distal limb.5,7 The effects of shoeing have been studied,4,5 specifi-
cally in relation to proprioception,8limb kinematics,9limb kinetics10
and energetics.11 The findings from these studies indicate that the use
of horse shoes is not a panacea and involves some potentially delete-
rious effects on soundness. This has stimulated an interest in main-
taining hooves without shoes and advocates have provided anecdotal
observations to support keeping horses barefooted and trimming
the hooves in a manner that is believed to promote the health of
the unshod hoof.12,13 However, there is a need to evaluate the effects
of barefoot trimming techniques under modern management
conditions.
Studies of wild horses have described the hoof as having a variable
shape that is based on a more or less rounded circumference with
natural bevelling at the toe, the medial wall and the lateral wall, while
the soles can be flat with protruding frogs or concave (arched soles).12
Ovnicek et al.14 described four imprint marks located medially and
laterally at the heels and toe, a finding that formed the basis for the
four-point trim for both shod and barefooted horses. The four-point
trim was subsequently shown to be associated with areas of strain
concentration above the hoof contact points when weight-bearing on
a firm surface.15 More recently, it has been shown that the substrate
over which the horse moves and the climate in which the horse lives
affect hoof morphology in wild horses.16 Consequently, there is no
uniform prescription for barefoot trimming. Given the different life-
styles and habitats of wild and domesticated horses, it is controversial
whether the wild horse hoof is an appropriate model from which to
develop principles for trimming barefooted domesticated horses.16
Some of the barefoot trimming methods that have been used have
resulted in short-term deleterious effects upon the horse’s foot due to
either excessive removal of tissues from the hoof wall, sole or frog or
by placement of the hoof and distal phalanx at an unnatural angle.12,13
The longer term effects of maintaining domesticated horses’ feet with
a barefoot trim have not been evaluated. Since the tissues of the foot
are responsive to their loading environment, it is hypothesised that
when the sole, frog and bars are incorporated in the weight-bearing
apparatus,these structures will hypertrophy and change biochemically
in response to locomotor forces. If this is true, then the barefoot trim
would be expected to induce changes in the size and shape of the
internal structures of the hoof, resulting in alterations in the external
morphology.17 It is expected that these changes would occur over a
prolonged period of time, requiring at least one entire growth cycle of
the hoof wall to begin to be evident.
The purpose of this study was to investigate the short- and long-term
effects of the barefoot trim on hoof conformation. The hypothesis is
that lowering of the heels to engage the frog, bars and sole into the
weight-bearing apparatus and shortening the foot by bevelling the
*Corresponding author.
Mary Anne McPhail Equine Performance Centre, Department of Large Animal Clinical
Sciences, and Department of Pathobiology and Diagnostic Investigation, College of
Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA;
claytonh@msu.edu
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toe, while maintaining the dorsopalmar and mediolateral balance of
the foot, will stimulate adaptations within the foot that result in sig-
nificant changes in its external dimensions. There is little scientific
data describing the effects of any type of barefoot trim, particularly
in horses that participate in regular exercise in a riding arena or how
such trimming may affect the overall conformation and health of
the foot for an extended period of time. Thus, the present study was
undertaken to trim a group of horses in a specific manner and to
document the changes in their feet by digital photography, radio-
graphy and quantitative measures over an extended time period
while they performed regular exercise.
Materials and methods
The study was performed with approval of the university’s animal
ethics committee.
Horses and farriery
The subjects were seven adult Arabian horses (height 149 3.2 cm;
mass 440 44.8 kg; age 13.6 1.6 years) that are used in a lesson
program at the undergraduate level of the university. The horses were
maintained on pasture and ridden in an arena with sand footing for
1 to 3 h/day, 5 days a week throughout the period of study, with all
horses receiving a similar workload. These horses had been barefooted
for a period of 3–4 years previously. The hooves had been allowed to
grow naturally with minimal farriery interventions for the previous
year. At approximately 8-weekly intervals the toe had been trimmed
and the wall rasped as necessary to maintain the toe angle in align-
ment with the pastern angle.
The barefoot trim of all four feet involved lowering the heels to allow
the frog and bars to contact the ground as active participants in the
weight-bearing apparatus. Dorsopalmar and dorsoplantar balances
were achieved by aligning the dorsal hoof wall (toe angle) with the
pastern axis. Mediolateral balance was initially achieved by trimming
to the depth of live sole, the waxy textured horn found beneath the
flaky superficial horn tissue of the sole.18 Ultimately, the goal was to
trim the wall and lower the heels to the level of the live sole as far back
as the widest part of the frog. The heels were lowered gradually over
the course of several trimming cycles to avoid creating a negative sole
plane for P3 or overloading the ligamentous tissues that support the
proximal and distal interphalangeal joints. The frog and bars were not
trimmed except to remove loose pieces of horn and excessive growth
that extended distal to the wall. The sole was not trimmed further after
it had been levelled to the live plane in the initial few trimmings;
instead, it was allowed to develop a sickle-shaped sole callus, which is
an area of thickened sole between the apex of the frog and the white
line at the toe. The wall external to the white line was bevelled around
the entire hoof with a rasp.
At the toe,the bevel initially included only the outer hoof wall and then
was gradually enlarged to the level of the white line and, as a sole callus
developed, the bevel was extended to the dorsal edge of the callus.
At the first evaluation (0-month evaluation), photographs and radio-
graphs were taken prior to trimming the hooves to describe the initial
shape of the foot. Each horse was then trimmed according to the above
prescription of the barefoot trim while maintaining the parallel align-
ment of the hoof-pastern axis. Trimming was repeated at intervals of
5–6 weeks, gradually lowering the heels to the level of live sole. By the
fourth trimming, the hooves conformed to these requirements but
had undergone minimal external adaptation to the new method of
trimming. Photographs and radiographs were taken one day after the
third trim, which was approximately 4 months after the start of the
study (4-month evaluation), and was regarded as the starting point for
measuring morphological changes in response to the barefoot trim.
The horses were then trimmed at 5–6 week intervals, maintaining the
prescription of the barefoot trim for a further 12 months.At the end of
this time, photographs and radiographs were taken 1 day after trim-
ming to assess the morphological adaptations to the barefoot trim
(16-month evaluation). Given that the initial length of the hoof wall at
the toe was (mean SD) 8.540.85 cm and the hoof wall grows at a
rate of about 1 cm/month in unshod horses,19 this was adequate time
for complete regrowth of the hoof wall.
Data collection
For all four feet, morphology of the hoof was assessed using lateral,
dorsal and solar view photographs and lateral view radiographs. For
the dorsal and lateral view photographs, the horses stood on wooden
blocks 5 cm high with a linear calibration in the plane of the coronet.
For the solar views, the hoof was raised and photographs were taken
with the calibration scale in the plane of the sole. For all photographs,
the camera lens was perpendicular to the plane in which measure-
ments were being made. Lateral view radiographs were taken with the
horse standing on a wooden block that incorporated a calibration
scale. Metron-PX software (EponaTech, Creston, CA, USA) was used
to measure linear and angular variables describing hoof conformation
and the relationship between P3 and the hoof wall. The following
variables were measured in each view:
Lateral View Photographs
Toe length to ground (cm) =length of dorsal hoof wall from hair-
line at coronet to ground plane.
Toe angle (degrees) =angle between dorsal aspect of hoof wall and
the ground plane.
Heel length (cm) =length of heel measured along its palmar/
plantar aspect from hairline to ground.
Heel angle (degrees) =angle between palmar/plantar aspect of heel
and ground plane.
Support length (cm) =length of the bearing surface of the distal
hoof wall excluding the bevel (Figure 1).
Dorsal View Photographs
Medial wall length (cm) =length of medial wall from hairline to
ground.
Medial wall angle (degrees) =angle between medial hoof wall and
solar plane.
Lateral wall length (cm) =length of lateral wall from hairline to
ground.
Lateral wall angle (degrees) =angle between lateral hoof wall and
solar plane.
Solar View Photographs
Solar area (cm2)=area within the periphery of the wall (includes
wall, sole, frog).
Frog area (cm2)=area within the periphery of the frog.
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Heel separation (cm) =distance between the medial and lateral
heels at the most palmar/plantar part of the wall.
Heel to bulb length (cm) =distance between a line connecting the
most palmar/plantar extent of the wall at the heels and a line
connecting the most palmar/plantar part of the bulbs.
Lateral View Radiographs
P3 to start of bevel at the toe (cm) =horizontal distance from the
dorsal tip of P3 to the start of the bevel which marks the point
where the hoof wall loses contact with the ground (Figure 1).
P3 solar angle (degrees) =angle between the solar surface of P3 and
the ground plane. Positive values indicate that the palmar/plantar
part of P3 is higher than the dorsal part.
Statistical analysis. Statistical software (SAS Institute Inc., Cary,
NC) was used to calculate descriptive statistics (mean, SD) for the
morphological variables at each evaluation. A GLM model for
repeated measures ANOVA was used to seek changes occurring
between 0 months and 4 months, which represented farriery changes
from the natural hoof shape to the barefoot trim, and changes between
4 months and 16 months, which represented adaptations in response
to maintaining the hoof with the barefoot trim. Preliminary statistical
evaluation indicated that fore and hind hooves were changing shape in
the same manner. Therefore, data for all limbs were combined in the
statistical model with the individual limbs being nested within horse.
The statistical tests used a significance level of P <0.05.
Results
Changes from 0 to 4 months
At the start of the study the hooves typically had long walls that were
flared around the periphery (Figure 2). The wall appeared to be the
main weight-bearing part of the foot since the frog, bars and sole were
recessed within the hoof wall. In most cases, the frog was fairly well
developed as judged by the fact that it protruded below the level of the
surrounding sole (Figure 2) but did not touch the ground when the
horse was standing on a hard surface. Some hooves had a small sole
callus in front of the apex of the frog.
Removal of the overgrowth of horn and shortening of the wall
between the 0-month and 4-month evaluations resulted in a smaller
Figure 1. Landmarks used to measure support length of foot (measured
from lateral view photographs) and distance from the distal phalanx (P3)
to the bevel at the toe (measured from lateral view radiographs).
Table 1. Mean SD of variables summarising morphological changes in all hooves (n =28) of 7 horses from the start of the study (0 months) and at
4 and 16 months after initiating the barefoot trim
Variable 0 months 4 months 16 months
Toe length to ground (cm) 8.54 0.85A7.87 0.42A,B 8.05 0.45B
Toe angle (degrees) 49.90 4.03A52.64 3.79A,B 51.45 3.16B
Heel length (cm) 3.30 0.56A2.63 0.28A2.64 0.27
Heel angle (degrees) 35.65 7.07 38.82 8.93B44.28 5.07B
Inner wall length (cm) 5.71 0.85A4.90 0.50A4.96 0.73
Inner wall angle (degrees) 73.62 5.89A78.62 5.46A78.31 5.66
Outer wall length (cm) 5.46 0.71A4.83 0.54A4.79 0.68
Outer wall angle (degrees) 72.36 4.91A76.02 4.77A75.68 3.60
Support length (cm) 11.20 1.23 10.93 0.62B11.59 0.56B
Solar area (cm2) 137.18 15.38A125.80 8.69A120.68 6.77
Frog area (cm2) 22.77 4.65A27.73 3.52A,B 24.40 2.96B
Heel separation (cm) 7.68 0.69A6.98 0.60A,B 6.57 0.68B
Heel-bulb length (cm) 2.72 0.62A2.10 0.46A1.73 0.35
P3 to bevel at the toe (cm) 3.77 0.59A2.82 0.38A2.89 0.41
P3 solar angle (degrees) 3.70 2.29A5.85 1.9A,B 7.38 2.06B
Significant differences over time were detected using repeated measures ANOVA and Tukey B post hoc tests with hoof nested within horse.
AVariables differ significantly (P <0.05) between 0-month and the 4-month evaluations.
BVariables differ significantly (P <0.05) between 4-month and the 16-month evaluations.
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hoof, shown by significant reductions in lengths of the toe, heel,
medial wall and lateral wall (Table 1, Figures 2, 3). Angles of the toe,
medial wall and lateral wall were significantly increased by the initial
shortening of the wall and removal of distal flaring. Heel angle did not
change significantly. The dorsal view at 4 months (Figure 2) showed a
distal deviation of the growth lines at the toe.
On the solar surface there were decreases in solar area, heel separation
and distance between the palmar/plantar aspect of the heels and the
bulbs, and an increase in frog area. On the radiographs, the distance
from the dorsal tip of P3 to the dorsal extremity of the weight-bearing
surface at the start of the bevel decreased, while the solar angle of P3
increased.
Figure 2. Photographs and radiographs of the right front hoof of one horse at the 0 month evaluation (left column), the 4-month evaluation (centre
column) and the 16-month evaluation (right column). The rows show from top to bottom: lateral view photographs, dorsal view photographs, solar
view photographs and lateral view radiographs.
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Changes from 4 months to 16 months
As the barefoot trim was maintained over the next 12 months, the
distal wall descended parallel to P3 without flaring toward the ground
surface. The position of the bevel at the toe relative to the tip of P3
was maintained and did not change during this period. Heel angle
increased significantly from 38.82oto 44.28owithout any change in
heel length (Table 1, Figures 2, 3) and the solar angle of P3 increased
from 5.85oto 7.38o. Heel separation decreased as the heels migrated
palmar/plantar to the frog and there was a trend toward a further
decrease in heel-bulb length that did not reach statistical significance.
The area of the frog decreased during this time.
Discussion
This study has shown significant changes in external morphology
of the hoof in response to barefoot trimming that are thought to be a
consequence of alterations in the shape and composition of the inter-
nal hoof structures in horses that performed a regular work schedule
in a riding arena with sand footing, compared with feral horses. Hoof
morphology at the start of the study resembled that of wild horses that
move over a relatively soft sandy substrate.16 Exercise affects the shape
of the hoof capsule, whereas P3 tends to retain its size and shape,thus
allowing it to act as a stable platform for supporting the capsule and
withstanding loads.20 The horses in this study had been accustomed
to a consistent exercise regimen for at least 4 years and this did not
change during the study, so it is unlikely that exercise, per se, was the
cause of the observed changes in hoof morphology. Furthermore,
since they had not been shod during the previous 4 years, the horses
already showed some adaptations to being barefoot, including having
a small sole callus and moderate frog development (Figure 2), which
may have facilitated and hastened the transition to the barefoot trim.
On the other hand, horses that have been shod continuously for a
prolonged period and those that enter a barefoot programme with
very long heels or atrophied frogs and bars may take considerably
longer than 4 months to make the transition to going barefoot.
Seasonal climatic changes may be associated with changes in hoof
shape. For example, in an area with wet winters and dry summers,
free-ranging horses had significantly lower hoof angles in winter than
in summer.21 Ideally, a group of controls would have been maintained
under the same management and exercise conditions, but it was not
possible to acquire a large enough number of horses to divide them
into two groups and retain sufficient statistical power to make inter-
group comparisons. Since the evaluations at 0 months and 4 months
were conducted at different times of year, it is possible that changes
during this period were influenced by the weather. However, the
4-month and 16-month evaluations were performed at the same time
of year, making it less likely that climatic changes affected differences
in hoof shape in response to maintenance of the barefoot trim.
At the start of the study, the hoof walls were somewhat overgrown in
spite of regular exercise in a sand arena. Hoof size and shape differed
markedly between individual horses at the start of the study (Table 1),
as shown by the large standard deviations that resulted in coefficients
of variation (CV) greater than 10% for many variables,especially those
describing linear dimensions of the hoof wall. The CVs tended to
decrease as the hooves were trimmed to conform to the barefoot trim.
The possibility cannot be ruled out that the hooves of some horses
may have already started to adapt internally during the initial
4 months and it is possible that the morphological changes measured
between 4 and 16 months may have underestimated the effects of the
barefoot trim. However, this should not affect the interpretation of the
results.
During the first 4 months of the study, many changes in hoof morph-
ology reflected alterations in the shape of the hoof that were a direct
result of the trimming procedure. Most of the linear dimensions of the
hoof decreased as a consequence of removing the wall overgrowth
that had accumulated during the period of self-trimming. The associ-
ated increases in angulation of the toe, medial wall and lateral wall
were due to removal of flaring of the distal wall associated with the
overgrowth of horn. Hoof wall strain is inversely related to the angu-
lation of the wall.22 Therefore, removal of flares resulting in a more
upright angulation of the medial and lateral walls would be expected
to generate lower strains within the wall and laminae. Also, there is
Figure 3. Mean hoof dimensions as seen in the lateral view at 0 month
(top), 4 months (middle) and 16 months (bottom).
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likely to be an effect on hoof loading and regional laminar density as
a consequence of reducing tensile stress that tends to separate the
walls from the laminae.23 The increase in toe angle during the initial
4-month period averaged 2.7o. A change of this magnitude over a
period of several months allows gradual adaptation of the internal
foot tissues and the tendinous and ligamentous structures that
support the proximal and distal interphalangeal joints. Therefore, the
gradual approach to achieving the required hoof shape at the start of
the study was unlikely to cause pathological changes in these tendo-
ligamentous structures in which strain is determined mechanically by
the interdigital angulations.24
During the 12-month period of maintenance of the barefoot trim, the
length of the hoof wall at the heel, medial wall and lateral wall did not
change significantly, while toe length increased by a small (0.18 cm)
but statistically significant amount. The hoof adapted to the increased
weight distribution on the frog and bars by a palmar/plantar migra-
tion of the wall at the heels, which was evident as an increase in
support length of the hoof. The heel angle became more upright,
which was associated with the distal part of the heels moving to a more
palmar/plantar position. When viewed from the solar surface, the
heels were seen to extend just palmar/plantar to the widest part of the
frog behind which the heels converged slightly resulting in a decrease
in heel separation The distance from the heels to the bulb was smaller
at the 16-month evaluation than at the 4-month evaluation but this
change did not reach statistical significance.
Heel angle increased by an average of almost 9oover the 16 month
study period as the heels appeared to migrate in a palmar/plantar
direction. Under-run heels, which have been defined somewhat arbi-
trarily in one study as having the heel angle more than 5oless than the
toe angle,25 are a significant problem in domesticated horses and may
contribute to catastrophic breakdowns.26 Heel angles similar to those
at the 16-month evaluation have been reported in a population of
Thoroughbred racehorses.27 The fact that the difference between toe
angle and heel angle decreased from 13.8oto 7.2oduring the period of
maintenance of the barefoot trim was regarded as a positive change.
We hypothesise that this was a consequence of bevelling the toe com-
bined with allowing participation of the frog and bars in the weight-
bearing function of the foot. The resulting increase in heel angle is
interpreted as a beneficial effect that would reduce the risk of injuries
associated with under-run heels.26
The unshod hoof deforms in response to loading during the stance
phase, whereas shoeing limits deformation of the hoof and expansion
of the bulbs.28,29 The heel region has an important proprioceptive
function mediated through the presence of Pacinian-like corpuscles
that are stimulated when the palmar/plantar foot contacts the
ground.8The sensory information is incorporated into spinal cord
reflexes during locomotion. Contact of the frog and bars with the
ground is believed to play an important role in shock attenuation.4In
addition, contact of the frog and bars may participate in a haemo-
dynamic mechanism that has been proposed to contribute to energy
dissipation by regulating blood flow through the palmar/plantar
foot.30 This suggestion is based on the fact that the microvasculature of
the palmar/plantar foot has numerous tachykinin receptors (NK1),
which, when activated, release endothelium-derived releasing factors
(nitric oxide) to promote vasodilatation.31–33 An increased microvas-
cular perfusion of the palmar/plantar foot may allow a more effective
dissipation of high-frequency impact energies generated when the
foot contacts the ground.28 Thus, a major benefit of the barefoot trim
is that it enhances the hoof’s ability to expand during weight-bearing,
which is important both in proprioception and shock absorption.
Frog area increased during the initial 4 months due to frog expansion
as a consequence of trimming the walls shorter, which allowed the
frog to make contact with the ground and appeared to stimulate
growth of the frog tissue as judged by the visual prominence of the
frog. During the period of maintenance of the barefoot trim, frog area
decreased, which might seem to be a contradictory finding. However,
histological evaluation of frog composition has shown a change from
predominantly fatty, elastic and myxoid tissue to fibrocartilage as the
frog is actively engaged in weight bearing.30 We hypothesise that, over
the 12-month maintenance period, the reduction in frog area may
have been a consequence of changing its composition from a loose
fatty material to a firmer, more resilient and compact texture of fibro-
cartilage. Contact between the frog and the ground may also contrib-
ute to changes in the internal structures of the foot, such as the digital
cushion, which is believed to be important in palmar support of the
foot. Future examination of the frog and digital cushion will have to
address these potential adaptations to changes in hoof shape and the
amount and type of exercise. Further indirect evidence of the benefit
of engaging the frog in the weight-bearing process may be provided by
the finding of aggrecanase-1 as an extra-cellular component of the
laminae.34 These molecules are typically found in tissues that sustain
compressive loading, which suggests that the laminae are intended to
be loaded in compression from below rather than suspending P3 from
the wall. This theory is consistent with the idea of spreading the load
across a greater solar surface of the foot.35 However, current knowl-
edge of hoof structure and dynamics is incomplete and these ideas,
while speculative, may provide a stimulus for further research.
In conclusion, the results presented here indicate that significant
morphological changes can take place in the hoof in response to the
barefoot trim. Palmar migration of the heels, which resulted in
increases in heel angle and support length, together with an increase in
solar angulation of P3 were interpreted as potentially beneficial to the
health of the foot.
Acknowledgments
The Bernice Barbour Foundation and the American Quarter Horse
Association provided financial support for this study.
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(Accepted for publication 16 January 2011)
Errataavj_812 311..317
Aust Vet J 2011;89:174–179
doi: 10.1111/j.1751-0813.2011.00704.x
Bilateral skin fold rotation-advancement flaps for the closure of large lumbosacral wounds in three dogs
A Dunn, E Buffa, R Mitchell and G Hunt
The following acknowledgments should have been presented in the above paper:
The authors would like to thank Dr Kate Patterson BVSc PhD for her anatomical illustrations.
Aust Vet J 2011;89:247–253
doi: 10.1111/j.1751-0813.2011.00793.x
Neurological diseases of ruminant livestock in Australia. II: toxic disorders and nutritional deficiencies
JW Finnie, PA Windsor and AE Kessell
The legend for Figure 2 was incorrect and should be as follows:
Figure 2. Ovine. Clostridium perfringens type D intoxication (a) Subacute, showing the bilateral, symmetrical necrosis (arrows) in the globus
pallidus. (Courtesy of the Atlas of Veterinary Neuropathology, College of Veterinary Medicine, Cornell University.) (b) Acute, showing severe
endothelial damage (arrows) in the cerebellum; the capillary lining is markedly attenuated and electron-dense. (electron micrograph).
Bar =10 mm.
EQUINE
EQUINE
© 2011 The Authors
Australian Veterinary Journal © 2011 Australian Veterinary Association Australian Veterinary Journal Volume 89, No 8, August 2011 311
... Barefoot trimming is, however, subject to some controversy within the industry. While there is some evidence that, when practiced properly, it can help correct problems such as under-run heels [44], it is not currently regulated by a governing body [45] and therefore lacks standardization. ...
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It is accepted that equine performance is directly influenced by hoof condition. Despite this, hoof abnormalities are the most frequent owner-reported cause of lameness and limited literature has evaluated hoof management practices. A survey was developed to establish the prevalence of hoof abnormalities in the UK, the corresponding routine treatments and to explore the client-farrier relationship. Of the respondents, 89% reported to have encountered hoof problems in the previous five years and routine use of hoof care products such as supplements and dressings was widespread. Whilst 96% of horses in the United Kingdom receive regular hoof care from a farrier, the client-farrier relationship has not previously been explored. It was found that 74% of respondents had worked with their farrier for more than two years; 41% however, had previously had difficulties finding a farrier they trusted. Of the respondents, 23% had a criticism of their farrier and 29% felt their farrier would have criticisms of their demeanour. It was suggested that both parties have a responsibility to one another in order to maintain an effective client-farrier relationship. Although certain supplements can be beneficial, scientific investigation is required to ascertain the efficacy of products such as hoof dressings on hoof growth and integrity. Furthermore, it would be of benefit to explore farrier and veterinary willingness to communicate and collaborate in order to provide optimal farriery. Cooperation between the professions has previously been highlighted as essential to therapeutic farriery but has not been investigated.
... Our dataset consisted of dorsal angles between 41 and 69 degrees. Forelimbs have been reported to ideally have angles between 45 and 50 [31], but experimental work has reported mean angles of around 50 [32,33]. This means our data included "normal" hoof angles as well as low (flat) and steep (upright) ones. ...
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Introduction Ground reaction forces in sound horses with asymmetric hooves show systematic differences in the horizontal braking force and relative timing of break-over. The Center Of Pressure (COP) path quantifies the dynamic load distribution under the hoof in a moving horse. The objective was to test whether anatomical asymmetry, quantified by the difference in dorsal wall angle between the left and right forelimbs, correlates with asymmetry in the COP path between these limbs. In addition, repeatability of the COP path was investigated. Methods A larger group (n = 31) visually sound horses with various degree of dorsal hoof wall asymmetry trotted three times over a pressure mat. COP path was determined in a hoof-bound coordinate system. A relationship between correlations between left and right COP paths and degree of asymmetry was investigated. Results Using a hoof-bound coordinate system made the COP path highly repeatable and unique for each limb. The craniocaudal patterns are usually highly correlated between left and right, but the mediolateral patterns are not. Some patterns were found between COP path and dorsal wall angle but asymmetry in dorsal wall angle did not necessarily result in asymmetry in COP path and the same could be stated for symmetry. Conclusion This method is a highly sensitive method to quantify the net result of the interaction between all of the forces and torques that occur in the limb and its inertial properties. We argue that changes in motor control, muscle force, inertial properties, kinematics and kinetics can potentially be picked up at an early stage using this method and could therefore be used as an early detection method for changes in the musculoskeletal apparatus.
... These conditions even at momentary or for intermittent periods of time may adversely affect sensitive hoof tissues. As a result many domesticated horses are shod, usually by nailing on a piece of metal to the bottom of the hoof wall, or in some cases, fixing it to the bottom of the hoof with glue (Back 2013, Clayton 2011, Curtis 2006, Hertsch et al. 1997, Humphrey 1995, Leisering et al. 1982, Leslie 1977, Möller 1915, Schwendimann 1937. ...
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From different reasons the hoofs of the horse should be protected in a manner that prevents easy frequent removal.The aim of this study was to assess one such method of temporary hoof covering, a hoof clog, to determine if application in horses trotting over hard ground affected vertical head and pelvic movement asymmetry measures of forelimb and hind limb lameness, compared to the normal shod and unshod (barefoot and just trimmed) condition. We were particularly interested in determining whether the hoof clog prevented any lameness that might develop in horses trotting barefoot on hard surface immediately after trimming. Twenty horses were randomly obtained from a riding school herd and evaluated objectively with their regular shoeing, barefoot and with a clogs applied using body mounted inertial sensors. Overall there were no significant differences in either group between treatments (regular shoeing, trimmed and unshod, clogs). Results of this study support the contention that applications of these hoof clogs do not cause forelimb or hind limb lameness, are well tolerated, and may decrease concussion when trotting on hard ground.
... Sows were used as their own control over time, following the equine hoof trimming model (Kummer et al., 2006;Clayton et al., 2011;Caldwell et al., 2016). Sows were not trained as no rewards were provided. ...
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Within the swine industry, lameness is one of the leading causes of culling and euthanasia of sows. Lameness negatively affects sow productivity and reproduction, both of which are major factors leading to culling sows. Claw lesions are one of the leading causes of sow lameness, specifically caused by overgrown claws or dewclaws. The objective of this study was to discern the difference in sow gait, pre- and post-functional trimming. In this study, 52 sows were functionally trimmed to a claw length of 5.5 cm from the coronary band, and were videotaped using two high-speed cameras at three time points: pre trim (PRE), one hour post (POST1) and 48 hours post (POST48) trimming. Videos were analyzed to measure the following spatiotemporal values: stance duration, swing duration, stride duration, stride length, limb velocity, breakover duration, and duration of three-limb support phases. Sows showed significant improvement in gait from PRE to POST48 in response to claw trimming including a decrease in swing and stride duration, decreased breakover, and increased swing:stance ratio, and velocity (P < 0.05). These changes signify more forward movement, which may indicate increased efficiency of gait following claw-trimming.
... This method of laminitis management apparently alleviated pain and returned this group of horses to their former level of athletic ability despite suspected minor to moderate nutritional imbalance, distal phalanx remodelling in some horses, and incomplete resolution of hoof wall rotation in some horses (Fig. 5). It is hypothesized that increased heel volume (Fig. 6) may in some way compensate for distal phalanx remodelling and laminar damage as altered heel dimension similar to the improved heel angles described by Clayton et al [23] was also noted in these horses. ...
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... Only recently, in relation to our domestication and use of the horse, we have had the ability to measure the forces and loads within the hoof and lower limb or the data collection and statistical techniques to quantify risk factors for injury [3,4] or longevity [5]. These data provide an understanding of the effect of different trimming and shoeing techniques [6] and also a scientific framework around which we can examine and quantify current practice [7]. ...
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This article describes the lower limb and hoof conformation of a population of semi-feral Mongolian horses living on an open tundra/steppe environment. Data were collected from a convenience sample of 120 Mongolian horses used in the 2011 Mongolian Derby. Digital images of the hooves were obtained, and the lower limb conformation was assessed by four veterinarians involved in the screening of the horses offered for the derby. The horses were predominantly geldings (96%, 100/104), approximately 8.6 ± 2.5 years old, and 137 ± 8 cm at the withers. None of the horses were subjected to routine hoof trimming. Based on a 7-point linear score, lower limb conformation was normal, with a trend (>1 linear score deviation) slightly toward carpal valgus, mildly offset cannon (third metacarpal), and valgus at the matacarpophalangeal joint. Hoof measurements were within the norm for horses of this size. Fetlock valgus was associated with a smaller hoof width:length ratio (P = .016). None of the other hoof measurements were significantly associated with abnormal conformation scores. Overall, few conformation abnormalities were observed, and hoof shape and size was within the normal expected range for horses of this size. The hoof conformation in this population of Mongolian horses represented the natural interaction of the hoof with the environment.
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Variation in equine hoof conformation between farriery interventions lacks research, despite associations with distal limb injuries. This study aimed to determine linear and angular hoof variations pre- and post-farriery within a four to six week shoeing/trimming interval. Seventeen hoof and distal limb measurements were drawn from lateral and anterior digital photographs from 26 horses pre- and post-farriery. Most lateral view variables changed significantly. Reductions of the dorsal wall, and weight bearing and coronary band lengths resulted in an increased vertical orientation of the hoof. The increased dorsal hoof wall angle, heel angle, and heel height illustrated this further, improving dorsopalmar alignment. Mediolateral measurements of coronary band and weight bearing lengths reduced, whilst medial and lateral wall lengths from the 2D images increased, indicating an increased vertical hoof alignment. Additionally, dorsopalmar balance improved. However, the results demonstrated that a four to six week interval is sufficient for a palmer shift in the centre of pressure, increasing the loading on acutely inclined heels, altering DIP angulation, and increasing the load on susceptible structures (e.g., DDFT). Mediolateral variable asymmetries suit the lateral hoof landing and unrollment pattern of the foot during landing. The results support regular (four to six week) farriery intervals for the optimal prevention of excess loading of palmar limb structures, reducing long-term injury risks through cumulative, excessive loading.
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Author's address: Department of Pathobiology and Diagnostic Investigation, Michigan State Uni-versity, East Lansing, MI 48824. © 2003 AAEP.
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The shape of the equine hoof capsule affects how weightbearing forces are resisted by the capsule and are transmitted to deeper structures within the hoof. Our aim was to isolate the effects of several measurements describing hoof shape on strains and stresses in the hoof capsule. Multiple finite-element models are constructed with toe angles in the range 42° to 58°, heel angles from 34° to 50°, toe lengths of 8.5 to 11.5 cm, and medial and lateral angles from 68° to 83°. Strain at the toe is inversely related to toe angle, and not strongly affected by heel angle; it increases with toe length distally on the toe, but decreases near the coronary border. Varying medial and lateral angles show that more upright walls have less strain at the quarters. This study demonstrates the effectiveness of finite element methods in complementing in vitro and in vivo studies of hoof mechanics.
The aims of this study were to determine whether the equine distal phalanx changes in shape in response to exercise and to relate any osseous changes to those in the hoof capsule. Eighteen mature Standardbred horses were randomly divided into exercise and control groups. Exercised horses were jogged on a straight track at individual mean speeds between 4 and 8 m s− 1 for 10–45 min, 4 days per week for 16 weeks. Both groups were similarly shod and pastured on the same field. Before and after the training period, each horse had digital photographs and magnetic resonance images (MRI) made of the right forehoof. Five linear measurements of the distal phalanx were recorded from the MRI and 24 measurements of the hoof capsule were made on the digital photographs. Small but significant changes in bone width (P = 0.039) were found in the controls and in two sagittal measurements of bone length (P = 0.039, 0.001, respectively) for the exercise group. These changes were slight and did not correlate with changes in shape of the hoof capsule, suggesting that the bone acts as a stable platform for supporting the capsule and withstanding loads.
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A modified standard friction test was used ex vivo to investigate static and dynamic coefficients of friction μs and μd between horses hooves and five substrates. Mean values for μs and μd (± standard error of the mean, SEM) were: 0·477 (0·010) and 0·281 (0·009) for steel, 1·024 (0·028) and 0·821 (0·018) for patterned rubber, 0·998 (0·019) and 0·846 (0·013) for smooth rubber, 0·887 (0·015) and 0·710 (0·013) for concrete, and 1·043 (0·017) and 0·638 (0·017) for HL3 grade asphalt.All coefficients were independent of the normal contact force (probability P>0·05). Comparison with ratios of horizontal and vertical force components between the hoof and ground, recorded in vivo, suggests that slip occurs in the first 25 ms of contact. The results also indicate the extent to which ground contact constrains the natural expansion of the lower border of the hoof under load.