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This is to certify that the

thesis entitled

The Relationship of Hoof Measurement
Parameters To Sole Contact and Distribution
In Adult Female Slaughtered Cattle

presented by

Douglas Eugene Hostetler

has been accepted towards fulfillment
of the requirements for

Master of Science degree 1,, Large Animal
Clinical Sciences

A/ K? I/Jfizém

Major professor

 

 

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1190 mm“

THE RELATIONSHIP OF HOOF MEASUREMENT
PARAMETERS TO SOLE CONTACT AND DISTRIBUTION
IN ADULT FEMALE SLAUGHTERED CATTLE
By

Douglas Eugene Hostetler

A THESIS
Submitted to
Michigan State University
in partial fiJlfillment of the requirements
for the degree of

MASTER OF SCIENCE

Department of Large Animal Clinical Sciences

1998

ABSTRACT
THE RELATIONSHIP OF HOOF MEASUREMENT
PARAMETERS TO SOLE CONTACT AND DISTRIBUTION
IN ADULT FEMALE SLAUGHTERED CATTLE
By

Douglas Eugene Hostetler

The objective of this study was to determine the relationship of the toe height, heel
height, and toe height to heel height ratio (T:H) to the area and distribution of sole contact
of the hind limbs in adult female cattle. Fifty-three distal hind limbs were collected from
adult female cattle presented to a local abattoir.

The toe and heel heights were measured, the flexor tendons attached to the
metatarsus, and the limbs were positioned in an Instron 8501M uniaxial testing machine.
Sole outlines were made and contact images were recorded on pressure-sensitive film at a
load of 1300 Newtons applied at a displacement rate of 0.25 mm/s.

The mean total sole contact was 1.89 cmz. The median contact of the lateral claws
significantly exceeded the mean contact of the medial claws by sixty-nine percent. The
majority of the sole contact was distributed in the dorsal and plantar two-thirds of the
lateral claw and the dorsal one-third of the medial claw. Low correlations between the

hoof measurement parameters and the area and distribution of sole contact were found.

ACKNOWLEDGMENTS

I would like to thank the members of my graduate committee, Dr. N. Kent Ames,
Dr. John Baker, Dr. John Caron, and Dr. Dianne Ulibarri, for their guidance on this
project. I would also like to thank Dr. Mike Ciarelli for invaluable guidance and assistance
during testing. His help made this project possible. I would also like to thank Dr. Steven
Amoczky and the Laboratory for Comparative Orthopaedic Research for the use of

laboratory equipment.

TABLE OF CONTENTS

LIST OF TABLES ........................................................................................................ vi
LIST OF FIGURES ...................................................................................................... vii
INTRODUCTION .......................................................................................................... 1
LITERATURE REVIEW ............................................................................................... 2
HYPOTHESIS ............................................................................................................. 12
MATERIALS AND METHODS .................................................................................. 13
Specimen Collection and Preparation ................................................................. l3

Limb Loading and Image Generation ................................................................. 14

Image Analysis .................................................................................................. 17
Experimental Design ......................................................................................... 19
Experiment 1: Fresh vs. Thawed Limbs .............................................................. l9
Experiment 2: Loading Cap Placement ............................................................... 19
Experiment 3: Loading Platform Composition .................................................... 20
Experiment 4: Main Study .................................................................................. 20
Statistical Analysis ............................................................................................ 21
RESULTS .................................................................................................................... 23
Results of Repeatability Experiments ................................................................. 23
Experiment 1: Fresh vs. Thawed Limbs ............................................................. 23
Experiment 2: Loading Cap Placement ............................................................... 26
Experiment 3: Loading Platform Composition .................................................... 28

Power Calculations for Experiment 4 ................................................................. 28
Experiment 4: Main Study .................................................................................. 28

Total Contact Between Left and Right Hooves ...................................... 28

Total Contact Between Medial and Lateral Claws .................................. 30

Claw Contact in Zones ........................................................................... 32

Correlation Analysis .............................................................................. 36
DISCUSSION .............................................................................................................. 42

iv

CONCLUSIONS .......................................................................................................... 57

APPENDICES ............................................................................................................. 59
Appendix A ....................................................................................................... 59
Appendix B ....................................................................................................... 6O

BIBLIOGRAPHY ........................................................................................................ 62

Table 1

Table 2

Table 3

Table 4

LIST OF TABLES

Spearman Rank Order Correlation coefficients (R) for the toe height, heel
height, and toe height to heel height ratio (T11) of the lateral claw vs. claw
contact area in lateral claw zones (N=53). Statistically significant p values
are highlighted. ...................................................................................... 38

Spearman Rank Order Correlation coeficients (R) for the toe height,

heel height, and toe height to heel height ratio (TzH) of the medial claw

vs. claw contact area in medial claw zones (N=53). Statistically

significant p values are highlighted. ........................................................ 39

Spearman Rank Order Correlation coefficients (R) for the toe height, heel
height, and toe height to heel height ratio (T:H) of the lateral claw vs. the
percentage of total contact in lateral claw zone (N=53). ......................... 40

Spearman Rank Order Correlation coefficients (R) for the toe height, heel
height, and toe height to heel height ratio (TzH) of the medial claw vs. the
percentage of total contact in medial claw zones (N=53). Statistically
significant p values are highlighted. ........................................................ 41

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7.

LIST OF FIGURES

Hoof measurement parameters, A, toe height; B, heel height;

C, dorsal wall length; D, dorsal wall angle; E, diagonal hoof

length; F, claw length; G, sole width (adapted from Vermunt

and Greenough, 1993). ............................................................................ 5

Distal limb attached to loading cap and positioned in custom
loading jig on Instron prior to testing. .................................................... 16

Example of composite image file, contact image, sole outline,

and claw zone layers for hoof number 036 with registration

reference marks (arrows). The contact image and sole outline

layers are superimposed. The contact zones are labeled Lateral

Dorsal, Lateral Middle, Lateral Plantar, Medial Dorsal, Medial

Middle, and Medial Plantar. ................................................................... 18

Mean total hoof contact i l standard deviation for fresh and
thawed limbs, 1.76 i 0.30 cm2 and 2.26 i: 0.55 cm2, respectively
(N=7). ................................................................................................... 25

Mean total hoof contact i 1 standard deviation for initial and repeated
loading cap placement were 1.39 i 0.21 cm2 and 1.32 i: 0.21 cmz,
respectively (N=7). ................................................................................ 27

Median contact area for left and right hooves. The median total
contact areas for the hooves were 2.06 cm2 and 1.83 cm2 for right and left
hooves, respectively (N=8, p=0.33). ...................................................... 29

Column medians of contact area for lateral and medial claws.

The median contact areas were 1.26 cm2 and 0.38 cm2 for lateral and
medial claws, respectively (N=53, p<0.001). ........................................... 31

vii

Figure 8

Figure 9

Column medians for zone contact area in the lateral claw.

The contact area means were 0.48 cmz, 0.18 cm2, and

0.46 cm2 for the lateral dorsal (LD), lateral middle (LM),

and lateral plantar (LP) zones, respectively (N=53). ............................... 34

Column medians for zone contact area in the medial claw.

The contact area medians were 0.30 cmz, 0.00 cm2, and 0.00 cm2

for the medial dorsal (MD), medial middle (MM), and medial

plantar (MP) zones, respectively (N=53). ............................................. 35

viii

INTRODUCTION

Lameness is a major economic problem facing the dairy industry. Decreased milk
production, reproductive inefficiency, and involuntary culling are losses commonly
associated with lameness. Wells reports an incidence of 43 cases of lameness/ 100
cows/year of lameness in herds with systematic lameness detection (Wells, Trent, Marsh,
and Robinson, 1993) using a locomotion scoring system to determine the presence of
lameness and epiderniologic analysis to determine the incidence of lameness in 17 herds. It
was concluded in 1985 that economic losses exceeded $200 per lameness case (Amstutz,
1985). This report assigned 1985 dollar values to economic data presented in 1964
(Weaver, 1964).

Hoof conformation has been examined to classify dairy cattle for genetic
improvement and as a predisposing factor in the development of lameneSs (Vermunt and
Greenough, 1995). Previous investigators (Greenough, MacCallum, and Weaver, 1981,
Rebhun and Pearson, 1882, Ral, 1990, Kasari, 1993,) have proposed that hoof
overgrth leads to an increased incidence of clinical lameness. The proposed etiologies
would suggest, that as hoof overgrth occurs, pressure is redistributed towards the heel.
The relationship of hoof conformation to sole contact distribution has not been previously
examined. The current study was proposed to determine if difi‘erences in hoof

conformation alter the sole contact distribution of the bovine hindlimb.

LITERATURE REVIEW

The study of bovine lameness requires thorough a understanding of the normal
anatomy and growth characteristics of the bovine hoof. Normal growth of the hoof wall
occurs at the coronary band at a rate of approximately 5.0 mm per month (Greenough et
al., 1981). Greenough suggests that the growth of the wall is asymmetric. This suggestion
is based on the observed divergence of the growth rings, which are linear depressions in
the external wall indicating variable wall thickness, at the dorsal border of the wall. The
sole is produced by the corium of the sole. Sole growth has been determined to occur at a
rate of 6.0 mm per month (Greenough, Vermunt, and McKinnon, 1990). The junction of
the sole and wall is known as the white line, which is characterized by lack of pigment in
the tubular and interlaminar horn of this region.

The epidermis of the hoof consists of four layers, including the stratum
germinativum, the stratum intemum, the stratum medium, and the stratum extemum
(Greenough et al., 1981). The deepest layer is the stratum germinativum. Hoof matrix is
formed as cells of the germinal layer are forced toward the external surface of the
epidermis. The papillary arrangement of the dermis results in the formation of horn
arranged in tubules. The hoof matrix is composed of these tubules and intertubular horn.
As the replicating cells of the stratum germinativum proceed toward the surface the next

layer formed is the stratum intemum. The stratum intemum is also called the horny lamina.

3

The horny lamina is the deepest portion of the insensitive laminae. The stratum medium
comprises the thickest portion of the hoof. The external surface of the hoof is the stratum
extemum. The stratum extemum is derived from the periople and may be absent over the
majority of the hoof. During migration, the cells become keratinized as nutrient supply is
lost (Toussaint-Raven, 1985). Under optimal interaction of host, nutrition, and
environment, the rate of horn production should equal horn wear.

Hoof quality depends upon the environment, the rnicroarchitecture of the hoof, and
water content of the hoof horn material or matrix. The hardness of the horn matrix has
been shown to be directly related to the density of the tubules (Gunther, Anton, and
K'a'sterner, 1983). Normal, good-quality horn has been described as having a tubular
density of 80 tubules per mm2 in the wall and 16 tubules per mm2 in the sole (Politiek,
Distl, Fjeldaas, Heeres, McDaniel, Nielsen, Peterse, Reurink, and Strandberg, 1986). The
water content of the hoof, normally less than 25% (Fritsch, 1966), can also be related to
tubular density. Decreased tubular density can allow more water to be absorbed into the
intertubular matrix (Vermunt and Greenough, 1995). Exposure to moisture in the
environment can increase or decrease the water content of the hoof matrix (Vermunt and
Greenough, 1995).

Hoof conformation has been studied as a means of classifying dairy cattle for
genetic improvement and as a predisposing cause of lameness (V ermunt and Greenough,
1995). One report, a review of hoof conformation studies, described several measurement
techniques used to assess hoof conformation in cattle (Vermunt and Greenough, 1995).

One technique involves measurement of the dorsal wall length and determination of the

4
dorsal wall angle with a modified protractor (Hahn, McDaniel, and Wilk, 1984). Vermunt

reported that heel height, claw width, claw (sole) length, toe to heel height ratio (TzH),
diagonal claw length, and sole area measurements have been performed in trait heritability
studies, and that heritabilities and genetic variation for claw measurements and disorders
were high enough that genetic improvement in these traits could be achieved (Vermunt
and Greenough, 1995). The dorsal wall length is measured from the periople to the apex
of the toe. Dorsal wall angle determination involves placing a modified protractor on the
proximal three cm of the dorsal wall and measuring the angle between the dorsal wall and
the weight-bearing surface. Heel height is typically measured at the bulbs of the heel and is
the distance from the hair line to the ground (Vermunt and Greenough, 1995). Claw width
is the greatest distance between the axial and abaxial wall. Claw or sole length is the
length of the weight-bearing surface from the dorsal wall to the plantar aspect of the sole.
The toe height to heel height ratio is calculated by dividing the height of the toe at the
dorsal coronary band by the heel height. The diagonal length is the distance fi'om the distal
toe (apex) to the proximal aspect of the heel (horn-skin junction of the heel). The diagonal
is measured along the abaxial wall. The sole area, determined with sole imprints or hoof
tracings, is estimated by the product of the claw length and the claw width (Vermunt and

Greenough, 1995) since the weight-bearing surface of the sole is not rectangular.

   

 

  

 

Figure l Hoof measurement parameters, A, toe height; B, heel height; C, dorsal wall

length; D, dorsal wall angle; E, diagonal hoof length; F, claw length; G, sole
width (adapted from Vermunt and Greenough, 1995).

6
The majority of hoof conformation studies deal with heritabilities of claw traits and

selection of breeding stock based on these traits. Hahn et al. (1984), McDaniel (1994),
Smit, Verbeek, Peterse, Jansen, McDaniel, and Politiek, (1986), Baumgarter and Distl
(1990) demonstrated a moderate-to-high heritability for dorsal wall angle, dorsal wall
length, and heel height. Two studies concluded that the heritabilities of claw
measurements and claw disorders were of sufficient magnitude that these traits could be
used for genetic improvement (Politiek et al., 1986; Ral, 1990). Causal relationships
between lameness and hoof conformation are difficult to prove because change in
conformation may be a predisposing factor or the result of digital disease (Ral, 1990). Ral
also suggested that increased T:H were correlated to a high frequency of claw disorders,
abnormal conditions of the hoof that cause lameness (Ral, 1990).

Animals have been the subject of biomechanical studies Since the first kinematic
experiments involving cinematographic procedures in the late 18003. These early studies
utilized high-speed cinematography to evaluate locomotion patterns of the horse
(Muybridge, 1899). Advancement of biomechanics eventually led to development of
equipment to assess ground reaction forces, the external forces acting on the limb as a
result of contact with the ground. Early work with cattle involved measuring the vertical
component of the external forces acting on individual digits of the hindlimb by placing the
subject’s hoof on a platform and measuring the weight borne by each claw (Toussaint-
Raven, 1973). This platform measured only the vertical component of load with no
measurement of the load distribution on the claws. More recent studies involve the use of

force plates (Scott, 1988). Force plates incorporate piezoelectric devices or strain gauges

7

to measure ground reaction forces. In kinetic studies the forces are evaluated in the
vertical, medial-lateral, and anterior-posterior directions. Scott reported the use of a force
plate in conjunction with a pedobaroscope to evaluate the vertical ground reaction forces
and contact area in growing heifers (Scott, 1988). This report concluded that, at the time
of peak vertical force, the heel and abaxial wall regions of the hoof provided support.
While this study characterized the distribution of contact and vertical forces for the entire
limb, it did not examine the conformational changes associated with hoof growth, wear, or
trimming.

Determination of the external forces acting on the hooves involves examination of
the ground reaction forces applied to the digit. Previous biomechanical studies in cattle
have not evaluated forces acting within the digit. Scott (1988) suggested that the areas of
support (sole contact) can change with hoof growth, wear and corrective hoof trimming,
however, no data were presented in Scott’s study to support this suggestion. Based on
extrapolation from the literature on equine joint mechanics, increases in the T:H will
change the angle of the cofiin (distal interphalangeal joint), resulting in an increase in the
moment about the joint (Bartel, Schryver, Lowe, and Parker, 1978). A moment is the
product of the applied force and the perpendicular distance from the axis of rotation to the
point on the line of transmission of that force. An increase in the moment about the distal
interphalangeal joint would increase the load on the deep digital flexor tendon (Bartel et
al., 1978). Using Bartel’s mathematical model, increasing the moment about the distal

interphalangeal joint during midstance phase, when the metatarsal angle is perpendicular to

8

the ground, will shift the center of pressure in the caudal direction to the plantar area of
the sole.

Abnormal growth and wear of the bovine hoof are important predisposing factors
associated with lameness (Greenough et al., 1981). Abnormal rates of horn production
and horn wear can occur with modern agricultural practices. Elevated dietary protein
(Manson and Leaver, 1988) and high-energy diets (Greenough et al., 1990) required for
maximum productivity can lead to increased horn production. Intensive housing
commonly uses concrete flooring, which has been shown to alter the normal rates of wear
of the plantar region of the hooves (Hahn et al., 1986). As the dorsal wall lengthens,
weight is shifted to the caudal aspect of the sole near the sole heel junction (Kasari, 1993).
Scott has conducted biomechanical studies to examine the relationship between limb
loading and the pressures generated under the soles in cattle (Scott, 1988; Scott, 1989). In
a study using a pedobaroscope, it was reported that there was no significant difl‘erence in
contact area between fore- and hindlimbs and that, at the time of peak vertical ground
reaction force, the heels and abaxial walls provided support (Scott, 1988). A
pedobaroscope is a device that measures the sole contact by collecting video images of
distortions of refracted light caused by application of pressure on membrane-covered
glass. Later, Scott reported that there is often a symmetrical distribution of lesions
between contralateral feet and concluded that secondary lesions develop due to increased
loading in one limb in an attempt to unload the site of the primary lesion in the other limb
(Scott, 1989). This author suggested that the study of applied loads to the feet of cattle

was important to improve the understanding of mechanical factors associated with

9
lameness. There have been no published reports of the relationship between hoof

conformation and biomechanical properties of the bovine digit.

Evaluation of digital disease in cattle requires a thorough understanding of the
common conditions resulting in lameness. Common lameness conditions associated with
abnormal hoof conformation include laminitis, pododermatitis circumscripta, horn erosion,
and white line disease (Baggott and Russell, 1981). Laminitis is a multifactorial disease
resulting from the interaction of the host, infectious agents, and nutritional and/or
management factors. Infectious agents include bacterial agents that release endotoxins or
exotoxins and viruses that affect vascular permeability or result in decreased tissue
perfirsion. Nutritional or management causes of laminitis include elevated dietary protein
(Manson and Leaver, 1988) and excessive energy in diets (Greenough et al., 1990)
required for maximum productivity, subacute rumen acidosis as a result of inadequate
rumen bufi‘ering or decreased efi‘ective fiber intake (N ordlund, 1996), and slug feeding
behavior of cattle in response to social pressure, seasonal stresses, high ambient
temperature, or humidity (Guard, 1996). Subclinical, acute, subacute, and chronic
laminitis have been described in cattle. No clear distinction of the forms can be established
because the condition can progress from one form of laminitis to another. It has been
reported that the specific laminitis form observed is dependent upon the severity,
frequency, and duration of exposure to insults, and the genetic predisposition of the animal
affected (Mortensen, 1994).

Singh, using an endotoxin model of subclinical laminitis, examined the histological

changes associated with laminitis (Singh, Murray, and Ward, 1994b). Separation of the

10

matrix from the papillae and laminae was demonstrated. Blood and serum from
hemorrhage of the corium and/ or laminae was incorporated into the matrix, resulting in a
decrease of the horn quality. As horn production resumes, following an insult to the
corium or laminae, the blood and serum are included into the newly formed horn. As the
newly formed horn matures and moves toward the surface the petechial hemorrhage is
observed within the sole matrix.

Increased T:H can occur as a combination of two factors. As the toe lengthens,
due to the asymmetrical horn production, i.e., divergence of the growth rings at the dorsal
border, the T:H becomes larger. Horn grth is accelerated, especially in the dorsal wall
and sole. Accelerated wear of the damaged matrix of the plantar sole and heel can also
occur. Chronic laminitis has been associated with generally accelerated hoof growth or
production ( Mortensen, Vermunt, Smits, Enevoldsen, vanKeulen, Greenough, Bergsten,
Menzel, Brizzi, Pluvinage, Bargai, Murray, and Kelly, 1992).

Pododermatitis circumscripta lesions, also known as Rusterholz ulcers or sole
ulcers, are defined as granulation tissue protruding through a defect in the sole superficial
to the insertion of the deep digital flexor tendon to the distal phalanx (Greenough et al,
1981). In one study, pododermatitis circumscripta was the most frequently diagnosed sole
lesion resulting in lameness (Greenough and Vermunt, 1991). Possible etiologies for
pododermatitis circumscripta include localized avascularity of the corium at the site of
ulcer formation (Singh, Murray, and Ward, 1994), exostosis of the plantar aspect of the
distal phalanx at the insertion of the deep digital flexor tendon (Greenough et al, 1981),

and/or increased concussive forces at the sole heel junction (Rebhun and Pearson, 1982).

ll

Localized avascularity of the corium at the site of ulcer formation can occur as a result of
subclinical laminitis (Singh, Murray, and Ward, 1994). Exostosis of the plantar aspect of
the distal phalanx at the insertion of the deep digital flexor tendon occurs as a result Of

increased tension on the tendon (Greenough et al, 1981).

HYPOTHESIS

Increased toe height, decreased heel height, or an increased T:H leads to a plantar

redistribution of the sole contact.

Specific Aims

1) Examine the contact area of the sole under a standard load and testing protocol.

2) Examine the relationship between external measurements, toe height, heel height, and

T:H, and the contact area and contact distribution of the weight-bearing surface of the

hoof in cadaver limbs.

12

MATERIALS AND METHODS

Specimen Collection and Preparation

Right or left rear limbs were harvested from adult female cull cattle presented for
slaughter at a local abattoir'. The limbs were disarticulated at the tarsal-metatarsal joint.
The hooves were cleaned with a pressure washer and the specimens were frozen at -20° C
within 12 hours of collection.

Twenty-four hours prior to testing, the specimens were removed from the freezer
and allowed to thaw at room temperature. Initial measurements of the hoof parameters,
toe height, and heel height were collected (Figure 1). The soft tissues were removed {Tom
the proximal aspect of the limb segment to expose 10 cm of the metatarsal bone. The
proximal metatarsus was transected at 90° to the long axis with a band saw to ensure a flat
perpendicular loading surface. The deep and superficial flexor tendons were attached to
the metatarsus with a spiked washer and 4.5 mm cortical bone screw” to prevent
hyperextension of the fetlock and pastem during loading. A 3.5 mm hole was drilled

through both cortices at the mid-diaphyseal point perpendicular to the long axis of the

 

“ Marco Packing Co., Plainwell, MI
b Synthes (USA), Paoli, PA

13

14

metatarsus. The hole was tapped to accommodate a 4.5 mm cortical bone screw. The
fetlock and pastem were maintained in a neutral position during tendon attachment by

clamping the metatarsus in a vice with the sole surface perpendicular to the metatarsus.

Limb Loading and Image Generation

The limb was placed in a custom specimen jig ° (Figure 2). The angle of the long axis of
the metatarsus to the loading stem of the cap was measured on the anterior and lateral
aspect to maintain a parallel relationship. This ensured axial loading of the metatarsus. The
jig was attached to a 500 lb. load cell mounted on an Instron 8501 M uniaxial testing
machined. The loading platform consisted of an oak board 1.5 inches thick covered with a
clear plastic overlay marked with perpendicular registration lines in the anterior-posterior
and medial-lateral directions. The hoof was positioned on white copy paper and preloaded
to approximately 70 Newtons (N). The sole outline was traced and reference points were
marked at the edge of the paper for future analysis. The load was removed but the limb
remained suspended. The preload was reapplied with the hoof positioned on pressure-
sensitive film" (Appendix A). Once in place, a compressive load of 1300 N (300 lb.) was
applied to the proximal metatarsus to mimic normal weight-bearing force (Appendix B).

The load was applied at a displacement rate of 25 mm/min. The contact

 

° Engineering Research Department, Michigan State University, East Lansing, MI
d Instron, model 8501M, Canton, MA
° Fuji Superlow Pressure Prescale Film, Japan, Itochu International , New York, NY

15

distribution pattern of the hoof and registration marks were recorded on Fuji Superlow
pressure-sensitive film‘. The contact image and outline were then scanned on a flatbed
scanner; at 300 dots per inch (dpi). The contact images and sole outlines were saved to

disk as black-and-white image files.

 

f HP ScanJet 4P, Hewlett-Packard Co., Camas, WA

t
i
l
r
i
l

 

Figure 2 Distal limb attached to loading cap and positioned in custom
loading jig on Instron prior to testing.

17

Image Analysis

The contact image was opened using Adobe Photoshop 3.0g software and saved as a
composite file. The sole outline was then opened, copied, and pasted as a layer over the
contact image. The outline layer was then positioned over the contact (background) image
so that the reference marks on each image were superimposed.

The sole outline for each digit was divided into three equal parts, based on the
percentage of total sole length, to allow determination of dorsal, middle, and plantar zones
of the sole. This arbitrary division of the sole was accomplished by creating another layer
in the composite copied from a grid consisting of three equal sections. The grid was
positioned over each digit and scaled to the total length of the digit. The total composite
image, including the contact image, the sole outline, and zone grids, was saved (Figure 3).

The grid layer over a digit was selected. For each zone of the digit, contact
information was copied from the background layer, pasted, and saved as a new file. The
image protocol was repeated for each zone of each digit and saved on disk. The image for
each zone was then analyzed for contact area (cmz) using image analysis software
(Sigrnascan Pro Image 2.0“). Contact area for each zone of each digit was determined and

saved.

 

8 Adobe Systems, Mountain View, CA
" Jandel Scientific Software, San Rafael, CA

I:

18

 

 

 

 

 

 

 

 

 

Lateral Claw Medial Claw
Lateral Dorsal ' 0"" Medial Dorsal
\.
Lateral Middle Medial Middle
- <-
->
Lateral Plantar Medial Plantar

 

 

 

 

 

Figure 3 Example of composite image file, contact image, sole outline, and claw
zone layers for hoof number 036 with registration reference marks
(arrows). The contact image and sole outline layers are superimposed.
The contact zones are labeled Lateral Dorsal, Lateral Middle, Lateral
Plantar, Medial Dorsal, Medial Middle, and Medial Plantar.

19

Experimental Design
Potential sources of error identified were the effect of freezing of the specimens
prior to testing, the site of tendon attachment, loading cap placement, and the effect of the

loading platform composition.

Experiment 1: Fresh vs. Thawed Limbs

Experiments were performed to examine the potential effect of freezing and
thawing of the limbs on the sole contact distribution and area. Since all of the experimental
data was collected on frozen specimens it was decided to evaluate the effect of freezing on
a small number of replicates. Seven fresh limbs were prepared, tested, and then fi'ozen at —
20° C for 24 hours. The frozen limbs were then thawed at room temperature, 20° C, and
retested. The total contact areas were compared with a paired T-test to determine if a

large measurement difi‘erence was introduced by fi'eezing the specimens.

Experiment 2: Loading Cap Placement

The placement of the limb in the loading cap was examined on seven specimens by
testing each limb and repeating the test after removing the loading cap and repositioning
the limb in the cap with no rotation. The results were compared using a paired T-test to
determine if a large data collection error was introduced in the sole contact area by the

loading cap placement.

20

Experiment 3: Loading Platform Composition

In order to test the effect of the loading platform composition on the repeatability
of the experiment, a concrete platform was constructed in the same dimensions as the oak
platform. Six limbs were to be tested using this platform and the oak platform. The limbs
were tested on the oak platform, raised, and testing was repeated on the concrete
platform. During testing the surface of the concrete platform became visibly worn. Further

testing of the platform was discontinued and the images were deleted from the study.

Experiment 4: Main Study

The main study of the project was designed to determine if a correlation exists
between external hoof measurements, toe height, heel height, and T:H of each claw, and
the sole contact area and the distribution of sole contact between the sole zones of each
claw. Each rear limb was prepared and tested using the standardized protocol. Image
analysis was performed and the information was stored in a spreadsheet. After testing
twenty limbs, sample size calculations were performed in Sigma Stat 2.0i statistical
software using the variance of the twenty initial limbs, alpha error of 0.05, and a power of
0.80 to estimate the total number of samples required. Based on this information an

additional thirty-three limbs were tested.

 

IJandel Scientific Software, San Rafael. CA

21

Statistical Analysis

Nonparametric statistical testing was employed in some instances for the present
study due to a relatively small sample size and the fact that some of the data were not
normally distributed, i.e., non-gaussian. The spreadsheet information was opened in the
Sigrnastat 2.0g statistics program. Data from the spreadsheets were analyzed to determine
if statistically significant differences were observed in the total contact between left and
right hooves, between lateral and medial claws, and between contact or the percentage of
the total contact in the zones within each claw.

Total contact of the eight right hooves and eight randomly chosen lefi hooves were
examined utilizing the Mann-Whitney Rank Sum test to determine if the testing protocol
resulted in statistically significant differences in the contact observed. The total contact
data for lateral and medial claws of all fifty-three limbs were analyzed to determine if a
statistically significant difference in total sole contact was noted between the claws. The
Mann-Whitney Rank Sum test was also utilized in this case. Contact differences within the
claws were examined to determine if there was a significant difference in the contact
observed in the three zones of the claw. These data were analyzed using the Kruskal-
Wallis ANOVA on Ranks and all pairwise comparisons were made with the Student-
Newman-Keuls test.

Spearman Rank Order Correlation analysis was performed to determine if there
was a relationship between the toe height, heel height, or the T:H of each claw and the
contact area (cmz) or the percentage of the total contact that was observed in each zone of

the weight-bearing surface of the claw. Non-parametric testing was used in this analysis

22

since the dependent variable, % contact, was a percentage value and therefore restricted to
a value between 0 and 100. The statistical tests were performed using statistical software

(Sigma-Stat 2.0i or Microsoft Excel 5.0‘).

 

J'Microsofi Corporation, Bothell, WA

RESULTS

Results of Repeatability Experiments
The data acquired from the repeatability experiments were analyzed to determine if
statistically significant error would be introduced by using previously flozen limbs, the site

of tendon attachment, the loading cap placement, or the surface of the testing platform.

Experiment 1: Fresh vs. Thawed Limbs

Seven limbs were tested to examine repeatability of the total contact area (cmz) in
fresh and thawed limbs. The mean total contact areas i 1 standard deviation for the flesh
and flozen limbs were 1.76 i 0.30 cm2 and 2.26 i 0.55 cmz, respectively (Figure 4). The
total sole contact area data were analyzed with a Paired T-test to determine if significant
error was introduced by fleezing and thawing the limbs prior to testing. The results of the
Paired T-test were t=-l .88 with 6 degrees of freedom and p=0.l 1. Individual zone contact
data were also analyzed with a Paired T-test to determine if significant error was
introduced into zone contact information by freezing and thawing. The mean contact for
the lateral dorsal zone of the flesh limbs was 0.50 cm2 and 0.57 cm2 for the lateral dorsal
zone following the fleeze thaw cycle. The results of the Paired T-test for the lateral dorsal
zone were t=-0.98 with 6 degrees of freedom (N=7, p=0.36). The mean contact for the

lateral middle zone was 0.56 cm2 and 0.72 cm2 for the flesh and thawed limbs,

23

24

respectively. The results of the Paired T-test for the lateral middle zone was t=-0.907
with 6 degrees of freedom (N=7, p=0.40). The mean contact for the lateral plantar zone
was 0.34 cm2 and 0.31 cm2 for the flesh and thawed limbs, respectively. The results of the
Paired T-test for the lateral plantar zone was t=0.51 with 6 degrees of fleedom (N=7,
p=0.63). The mean contact for the medial dorsal zone was 0.19 cm2 and 0.27 cm2 for the
flesh and thawed limbs, respectively. The results of the Paired T-test for the medial dorsal
zone was t=-2.4S with 6 degrees of fleedom (N=7, p=0.05). The mean contact for the
medial middle zone was 0.11 cm2 and 0.25 cm2 for the flesh and thawed limbs,
respectively. The results of the Paired T-test for the medial middle zone was t=-2.48 with
6 degrees of fleedom (N=7, p=0.05). The mean contact for the medial plantar zone was
0.03 cm2 and 0.08 cm2 for the flesh and thawed limbs, respectively. The results of the
Paired T-test for the medial plantar zone was t=-2.76 with 6 degrees of fleedom (N=7,

p=0.03).

25

Mean Total Hoof Contact

 

i9

§

§

Total Hoof Qpntact (cm')
2

 

Figure 4

  

 

 

Fresh Thawed

Mean total hoof contact i 1 standard deviation for flesh and thawed
limbs, 1.76 i 0.30 cm2 and 2.26 i 0.55 cmz, respectively (N=7).

26

Experiment 2: Loading Cap Placement

The placement of the metatarsus in the loading cap was examined in seven limbs by
testing the limb, repeating the testing after each limb had been removed flom the cap and
repositioning the cap with no rotation.

The mean total hoof contact areas i 1 standard deviation for the initial and
repeated loading cap placement were 1.39 i 0.21 cm2 and 1.32 i 0.21 cmz, respectively.
The data were compared with a paired T-test to determine if there were large differences
in total claw contact associated with the position of the limb in the loading cap. Results of
the paired T-test included a t statistic of 0.670 with 6 degrees of fleedom and p=0.670.

The differences in the total hoof contact area were not significant (Figure 5).

Total Hoof Contact (an)

27

Man Tolal Hoof Contact

 

E

El

E

p
8

p
8

p
8

 

 

Initial

CapPlaeement

Figure 5 Mean total hoof contact i 1 standard deviation for initial and repeated
loading cap placement were 1.39 i 0.21 cm2 and 1.32 i 0.21 cmz,
respectively (N =7).

 

28

Experiment 3: Loading Platform Composition

The surface of the loading platform was examined to determine the difference in
observed contact area and distribution as a result of the platform composition. Six limbs
were scheduled for examination. Visible wear of the surface of the concrete in the region
of toe contact occurred during testing. The concrete platform testing and analysis were
discontinued and the samples were deleted flom the study due to the altered surface

smoothness of the concrete platform.

Power Calculations for Experiment 4
Based on power and sample size calculations following the preliminary testing of
twenty limbs, it was estimated that a total of fifty limbs would require testing to achieve a

power of 0.80 at an alpha error (p) of 0.05.

Experiment 4: Main Study
Total Contact Between Left and Right Hooves

The total contact area between left and right hooves was evaluated to determine if
the testing protocol introduced significant differences in the contact between lefi and right
hooves, potentially altering the results of medial and lateral digits. The median total
contact areas for the hooves were 2.06 cm2 and 1.83 cm2 for left and right hooves,
respectively. The total contact area was analyzed using the Mann-Whitney Rank Sum
Test (p=0.33, N=8) (Figure 6). No significant difl‘erence was noted between left and right

hooves. The mean total sole contact for all hooves in the study was 1.89 cm2 (N=53).

29

Median Contact Area

 

- N
ail-NU:

9
01

Total Contact Area
(cmz)

 

Figure 6 Median contact area for left and light hooves. The
median total contact areas for the hooves were 2.06 cm2 and
1.83 cm2 for lefi and light hooves, respectively (N=8, p=0.33).

30

Total Contact Between Medial and Lateral Claws

The total sole contact areas of the lateral and medial claws were examined to
determine if there was a statistically significant difference in the sole contact between
claws. The median contact areas were 1.26 cm2 and 0.38 cm2 for lateral and medial claws,
respectively. The median sole contact area of the lateral claws exceeded the median sole
contact area of the medial claws by 69 percent. The data for total sole contact of the claws
were examined using the Mann-Whitney Rank Sum Test and a statistically significant
difl‘erence was observed. (N=53, p<0.001) (Figure 7). This finding indicates that there is a

statistically significant diflerence in sole contact area between the lateral and medial claws.

Total Contact

31

Median Contact Area

 

Area (cmz)

 

 

 

Lateral Medial
Claw

Figure 7 Column medians of contact area for lateral and medial
claws. The median contact areas were 1.26 cm2 and 0.38 cm2 for
lateral and medial claws, respectively (N=53, p<0.001).

32

Claw Contact In Zones

The sole contact areas in the lateral dorsal (LD), lateral middle (LM), lateral
plantar (LP), medial dorsal (MD), medial middle (MM), and medial plantar (MP) zones of
the claws were examined to determine if statistically significant difl‘erences in sole contact
were observed between the sole surface zones within the claw. The data were first
analyzed with the Kruskal-Wallis ANOVA on Ranks (K-W ANOVA) to determine if
statistically significant differences in sole contact were observed. A multiple pairwise
comparison was then performed with the Student-Newman-Keuls (SNK) Test. The
median sole contact areas for the zones of the lateral claws were 0.483 cmz, 0.175 cm2,
and 0.464 cm2 for the LD, LM, and LP zones, respectively. The results of the K—W
AN OVA for the lateral claw revealed statistically significant diflerences between the sole
contact areas of the LD, LM, and LP zones (l-l=26.77 with 2 degrees of freedom) (p<
0001, N=53). The median sole contact areas for the zones of the medial claws were 0.295
cmz, 0.00 cm2, and 0.002 for the MD, MM, and MP zones, respectively. The results of the
K-W ANOVA for the medial claw revealed statistically significant differences between the
sole contact areas of the MD, MM, and MP zones (H=76.9l with 2 degrees of freedom)
(p< 0.001, N=53).

Statistically significant differences in the column medians for sole contact area
were observed for both the lateral (Figure 8) and medial (Figure 9) claws. The median sole
contact area (cmz) in the LD (0.483 cm2) and LP (0.464 cmz) zones had significantly
greater sole contact areas than the LM zone (0.175 cmz) (Figure 8). The median sole
contact area (cmz) in the MD zone (0.295 cmz) had significantly greater sole contact area

than the MM (0.00 cmz) or the MP (0.00 cmz) zones (Figure 9). The SNK testing

33

performed on the data flom the lateral claw zone contact areas revealed statistically
significant differences between the LD and LM zones as well as statistically significant
differences between the LM and LP zones (p<0.05, N=53). The SNK performed on the
data from the medial claw zone contact areas revealed statistically significant differences
between the MD and MM zones as well as between the MD and MP zones (p<0.05,
N=53). Sole contact in different areas of the sole of the lateral and medial claws were

indicated by these results.

 

Median Contact Area
1
0.9 I
0.8 -
0.7 +
0-6 “L 0.483 0.464

 

 

Contact Area (cmz)

 

Lateral Dorsal Lateral Middle Lateral Plantar
Claw Zone

Figure 8 Column medians for zone contact area in the lateral claw. The
median contact areas were 0.48 cmz, 0.18 cm2, and 0.46 cm2
for the lateral dorsal (LD), lateral middle (LM), and lateral plantar
(LP) zones, respectively (N=53).

35

Median Contact Area

v 0.7

 

0.00 0.00

Medial Dorsal Medial Middle Medial Plantar
Claw Zone

Figure 9 Column medians for zone contact area in the medial claw. The
contact area medians were 0.30 cm2, 0.00 cm2, and 0.00 cm2
for the medial dorsal (MD), medial middle (MM), and medial
plantar (MP) zones, respectively (N=53).

36

Correlation Analysis

Spearman Rank Order Correlations were performed on the fifty-three limbs
included in the main study to examine the relationship between the measured toe height,
heel height, and T:H on the total sole contact area (cmz) recorded in each zone of the
lateral and medial claws (Table 14). No significant correlation existed for the comparison
of the lateral toe height and the total sole contact area (cmz) in the LD, LM, or the LP
zones. Comparison of the medial claw toe height to the sole contact area (cmz) in the
MD, MM, and MP zones revealed significant correlation (p=0.01) between the medial toe
height and sole contact area (cmz) in the MM zone. The correlation coeficient (R) was
0.34 for the comparison of the medial toe height and sole contact area (cmz) in the MM
zone.

Correlation analysis using the Spearman Rank Order Correlation was performed to
examine the relationship between the heel height and the sole contact area (cmz) in the
dorsal, middle, and plantar zones of the respective claw. Significant low correlations were
found between the lateral claw heel height to the sole contact area (cmz) in the LP zone
and between the medial claw heel height and contact in the dorsal and middle zones of the
medial claw. The correlation coefficients (R) were -0.28, 0.27, and 0.35, respectively. The
p values were 0.04, 0.05, and 0.01, respectively.

Correlation analysis was performed for the lateral and medial T:H and the sole
contact area (cmz) in the LD, LM, and LP, and the MD, MM, and MP zones respectively.

Significant correlation (R=0.33, p=0.02) existed between the lateral claw T:H and contact

37

in the LP zone. A significant relationship also existed between the medial claw T:H and
contact in the MD zone (R=-0.32) (p=0.02) (N=53).

Linear regressions were not performed to examine the predictive ability of the
measured lateral and medial claw toe height, heel height, and T:H on the percentage of
total sole contact observed in each zone of the respective claw because the correlations
between the variables were small.

No significant relationship between the toe height, heel height, or T:H of the lateral
claw and the percentage of claw contact in the LD, LM, or LP zones were found when
Spearman Rank Order Correlation analysis was performed. Significant correlation was
detected between the medial claw toe height and the percentage of total claw contact in
the MD, (R=-0.28) (p=0.04), and MM, (R= 0.34) (p=0.01) zones. The analysis of the
relationship between medial claw heel height and the percentage of the total claw contact
area in the dorsal, middle, and plantar sole zones of the respective claw revealed a
significant relationship (p=0.02) only between the medial claw heel height and the
percentage of total claw contact in the middle zones of the medial claw. The correlation
coeflicient (R) was 0.32 for the comparison of the medial claw heel height and the
percentage of the total claw contact in the MM zone. No significant relationship was
found between the T:H and the percentage of total claw contact in the zones of the medial

claw.

38

Table 1 Spearman Rank Order Correlation coefficients (R) for the toe height, heel height,
and toe height to heel height ratio (T:H) of the lateral claw vs. claw contact area
in lateral claw zones (N=53). Statistically significant p values are highlighted.

 

Spearman Rank Order Correlation N R p
value

 

Toe Height vs. Contact in Lateral Dorsal Zone 53 -0.09 0.54

 

Toe Height vs. Contact in Lateral Middle Zone 53 -0.23 0.09

 

 

 

 

 

 

Toe Height vs. Contact in Lateral Plantar 53 0.23 0.10
Zone
Heel Height vs. Contact in Lateral Dorsal Zone 53 -0.05 0.72
Heel Height vs. Contact in Lateral Middle 53 0.04 0.77
Zone
Heel Height vs. Contact in Lateral Plantar 53 -0.28 0.04
Zone
T:H vs. Contact in Lateral Dorsal Zone 53 -0.06 0.69
T:H vs. Contact in Lateral Middle Zone 53 -0.08 0.58

 

 

T:H vs. Contact in Lateral Plantar Zone 53 0.33 0.02

 

 

 

 

 

39

Table 2 Spearman Rank Order Correlation coefficients (R) for the toe height, heel height,
and toe height to heel height ratio (T:H) of the medial claw vs. claw contact area
in medial claw zones (N=53). Statistically significant p values are highlighted.

 

Spearman Rank Order Correlation N R p
value

 

Toe Height vs. Contact in Medial Dorsal Zone 53 0.06 0.65

 

Toe Height vs. Contact in Medial Middle Zone 53 0.34 0.01

 

Toe Height vs. Contact in Medial Plantar 53 0.16 0.24
Zone

 

Heel Height vs. Contact in Medial Dorsal Zone 53 0.27 0.05

 

 

 

 

Heel Height vs. Contact in Medial Middle 53 0.35 0.01
Zone
Heel Height vs. Contact in Medial Plantar 53 0.11 0.42
Zone
T:H vs. Contact in Medial Dorsal Zone 53 -0.32 0.02
T:H vs. Contact in Media] Middle Zone 53 -0.16 0.26

 

 

T:H vs. Contact in Medial Plantar Zone 53 -0.06 0.69

 

 

 

 

 

40

Table 3 Spearman Rank Order Correlation coefficients (R) for the toe height, heel height,
and toe height to heel height ratio (T:H) of the lateral claw vs. the percentage of

total contact in lateral claw zone (N=53).

 

 

 

 

 

 

 

 

 

 

 

Spearman Rank Order Correlation N R p
value

Toe Height vs. % Contact in Lateral Dorsal 53 -0.03 0.80
Zone

Toe Height vs. % Contact in Lateral Middle 53 -0.02 0.09
Zone

Toe Height vs. % Contact in Lateral Plantar 53 0.23 0.10
Zone

Heel Height vs. °/o Contact in Lateral Dorsal 53 -0.24 0.08
Zone

Heel Height vs. % Contact in Lateral Middle 53 -0.10 0.47
Zone

Heel Height vs. % Contact in Lateral Plantar 53 0.20 0.16
Zone

T:H vs. % Contact in Lateral Dorsal Zone 53 0.20 0.16
T:H vs. % Contact in Lateral Middle Zone 53 0.07 0.61
T:H vs. % Contact in Lateral Plantar Zone 53 0.17 0.21

 

 

 

 

 

41

Table 4 Spearman Rank Order Correlation coefficients (R) for the toe height, heel
height, and toe height to heel height ratio (T:H) of the medial claw vs. the
percentage of total contact in medial claw zones (N=53). Statistically significant

 

 

 

 

 

 

 

 

 

 

 

p values are highlighted.
Spearman Rank Order Correlation N R p
value

Toe Height vs. % Contact in Medial Dorsal 53 -0.28 0.04
Zone

Toe Height vs. % Contact in Medial Middle 53 0.34 0.01
Zone

Toe Height vs. % Contact in Medial Plantar 53 0.12 0.37
Zone

Heel Height vs. % Contact in Medial Dorsal 53 -0.18 0.20
Zone

Heel Height vs. °/e Contact in Medial 53 0.32 0.02
Middle Zone

Heel Height vs. % Contact in Medial 53 0.07 0.63
Plantar Zone

T:H vs. % Contact in Medial Dorsal Zone 53 0.02 0.92
T:H vs. % Contact in Medial Middle Zone 53 -0. 14 0.30
T:H vs. % Contact in Medial Plantar Zone 53 -0.03 0.81

 

 

 

 

 

DISCUSSION

Several points regarding the design of the present study should be addressed,
including the anatomic landmark for measurement of the heel depth, pressure-sensitive
film selection, the total load applied to the limb, the displacement rate, the site of tendon
attachment, the loading platform construction, and the use of frozen specimens.

Heel depth in the present study, the distance from the proximal aspect of the
abaxial groove to the sole, was measured perpendicular to the sole. This method differs
only slightly from the technique reported in the literature (Vermunt and Greenough, 1995)
and allows the use of a consistent anatomic landmark. Differences in the axial and abaxial
heel height on each claw will not affect this measurement. This measurement technique
also provides other investigators the ability to repeat the measurement with accuracy.

The most sensitive film available was selected because the researcher’s intent was
to detect the maximum amount of sole contact. Less-sensitive film could have been used
that would have allowed densiometric evaluation of pressure distribution. Selection of
less-sensitive film would also result in loss of the areas with minimal contact pressure and
would therefore decrease the total contact area recorded. With the selection of the most
sensitive film available, the areas of contact that exceeded the upper level of pressure
sensitivity of the film produced maximum indicator density (saturation) on the film.

Saturation of the film results in loss of the ability to detect the pressure gradient

42

43

using a densiometer. Pressure and load distribution information were beyond the scope of
the present study.

The total load applied to the specimens in this study was chosen to mimic the
normal load applied to a rear digit in a standing adult cow. The total load in this study
(1300 N) was selected as slightly higher than one fourth of the average live weight (550
kg) of the adult cattle presented for slaughter on the day the specimens were collected.
Although Scott reports that only 45% of the body weight is supported by the hindlimbs in
cattle at rest (Scott, 1988), the peak loading in this study represented transient weight
shifting to rest the contralateral limb.

The displacement rate of 25 mm per minute was selected to allow gradual and
controlled loading of the tendons and ligaments. A rapid loading rate might have caused a
difference in the contact image due to the relatively elastic response of the tendons and
ligaments of the distal limb. The slower loading rate was elected to ensure integrity of soft
tissues as tendon and ligament failure is dependent on loading rate. The rate chosen
allowed the operator to suspend loading and maintain displacement as the maximum load
was applied.

The utilization of commercially available software for image analysis precluded
expensive and time-consuming customized programming for image analysis. Commercially
available software also had the benefit of providing readily accessible professional
technical support. The use of commercially available software would also enable other

researchers to easily repeat or expand the present study.

44

Tendons were attached to the metatarsus at fifty percent of the metatarsal length in
the present study to for several reasons. Fifty percent of the metatarsal length was chosen
because this site is easily identified. This site posed no interference with loading cap
placement. Screw and spiked washer placement at fifty percent of the metatarsal length
attached the flexor tendons proximal to the site where the tendons divide to act on each
digit. No significant error was introduced by the site of tendon attachment.

The placement of the limb in the loading cap, Experiment 2, did not significame
alter the contact area observed in the present study. These limbs were loaded on the oak
platform before and after removal and replacement of the loading cap.

The oak loading platform was used in this study to allow a smooth, flat, hard
surface for loading that would allow height adjustment for anatomic variation of the
metatarsal length. A concrete platform was constructed and initially tested but was
abandoned as wear of the concrete in the toe region altered the surface of the platform.
While concrete would more accurately mimic the surface on which most confined cattle
walk, a gradually changing surface would have resulted in loss of contact information in
later specimens. Repeating this study with in vivo testing on concrete may produce data
that would more accurately mimic the sole contact occurring in the normal environment of
cattle on concrete. The lack of significant differences in the loading cap experiment led the
researcher to conclude that the loading platform did not significantly affect the
repeatability of the experiment.

There was no significant difference in the contact observed between the left and

right hooves. This finding supports literature reports citing no difference in the loading of

45

contralateral limbs during kinetic studies (Scott, 1988). No significant error was
introduced related to the selection of left or right hooves for the present study. If the
protocol had introduced more contact in either lefl or right hooves, a difference should
have been noted.

During Experiment 1, it was noted that the total sole contact in limbs that were
frozen, thawed, and tested exceeded the total contact in the previously tested fresh limbs
by twenty-eight percent (Figure 4). While this finding was not statistically significant at a
significance level of 0.05, the p value of 0.11 approaches the level of significance for total
sole contact. The mean contact area in the lateral dorsal zone of the thawed specimens
was 14% greater than the mean contact area in this zone of the fresh specimens. The mean
contact area for the lateral middle zone increased 30% as a result of the freeze-thaw cycle.
The mean contact area of the lateral plantar zone decreased 8% following the freeze-thaw
cycle. The differences in contact in the zones of the lateral claw as a result of freezing and
thawing are not statistically significant, however the amount of change in the mean contact
area is of note. The differences of the mean contact in the zones of the medial claw as a
result of the freeze-thaw cycle are statistically significant. The mean contact in the zones
of the medial claw increased 42%, l27%, and 166% for the dorsal, middle, and plantar
zones, respectively. The observed difference in sole contact may be a result of tissue
changes occurring in the sofi tissues of the limb during the freeze-thaw cycle. In order to
control the site of tendon attachment during the thawed specimen test, the limb was frozen
following the fresh specimen test with the attachment screw in place. During the freezing

and thawing process the tendons may have stretched resulting in an alteration of the

46

tension on the flexor tendon during loading. Freezing and thawing may also have had an
effect on the digital cushion resulting in altered loading of the sole. This suggests that
caution should be exercised when comparing the results obtained from thawed limbs to
those obtained flom fresh limbs. Due to logistic problems encountered with sample
collection and scheduling mechanical testing, flesh limbs could not be utilized for the
present study. Tissue degeneration as a result of prolonged storage precluded the use of
flesh limbs for mechanical testing.

The present study made several contributions to the body of information on the
biomechanics of the bovine digit. These contributions include additional information on
the area and distribution of sole contact in cattle. The mean total rear hoof contact area
information collected during the present study (1.89 cmz) is slightly higher than the data
presented by Scott for the contact area in the rear hooves (Scott, 1988). The observed
discrepancy may have occurred as a result of several factors. This discrepancy is expected
since the limbs utilized in the present study were obtained from adult female cattle,
whereas the previous work involved measuring the total sole contact area of the hooves of
growing maiden heifers over a six-month period.

The previous results cited (Scott, 1988) were obtained flom in vivo testing,
whereas the present study evaluated in vitro sole contact of thawed, previously frozen
limbs, at a standard compressive load. The present study demonstrates that the sole
contact is increased following a freeze-thaw cycle. During in vivo testing the magnitude of

the applied load may vary with the individual subject. If the sole contact area is dependent

47

upon the compressibility of the sole matrix, greater contact may occur if the sole is
subjected to a larger peak compressive load.

The value presented as the total sole contact area in Scott’s study was the sum of
medial and lateral rear claw mean contact areas listed for the final samples obtained in the
study. By choosing the final samples obtained from the six maiden heifers, the contact area
estimates should be the means fi'om the oldest age group in the study. This estimate is
from maiden heifers and some growth potential may remain.

Whether the mean sole contact area obtained flom adult female cattle is better to
evaluate than data from younger heifers depends upon the focus of the study. if analysis of
the sole contact area changes associated with somatic growth is the primary focus of the
study, then following heifers through maturity would be the best population subset to
evaluate. If, however, the changes in hoof conformation and/ sole contact associated with
gestation, lactation, nutrition, environment, infectious diseases, or seasons are the focus,
then the study should be performed on mature cattle to decrease the influence of skeletal
growth on the parameter of interest.

An interesting observation from the sole contact area data obtained from the
present study was that the total sole contact observed on a flat smooth surface was smaller
than the researcher expected. That a tremendous amount of weight is borne over a
relatively small sole surface area was implied by this finding. The pressure, defined as the
applied force divided by the area of application, generated over this small sole contact area
would thus be quite large. The observed small contact area may be due to an irregular sole

surface resulting from abnormal wear of the sole. The sole contact would be much greater

48

if the limb were loaded on a compressible surface, such as dirt or sand and therefore
dissipate the large pressures generated under the sole. The dissipation of load would
potentially decrease the prevalence of lameness in a herd. The potential for traumatic insult
to the sensitive structures of the hoof, the corium and sensitive lamina, would suggest
chronic cyclic overloading as a potential etiology for development of
laminitis/inflammation of the corium. If, as suggested, chronic cyclic overloading is a
contributing factor in the development of laminitis, studies examining this relationship
would be beneficial. One potential method to examine this relationship would be to
evaluate the sole load distribution in cattle with no evidence of laminitis, and to repeat the
testing of these cattle at regular intervals making observations of lesions associated with
subclinical laminitis in the herd. The image analysis protocol utilizing digital photography
previously described could be used for determination of lesion distribution. Analysis of
the results of the prospective study would determine if the sole load distribution was
related to the distribution of subclinical laminitis lesions in the herd.

Statistically significant differences were found in the contact between lateral and
medial claws (p<0.05). These findings agree with the findings of Peterse (I985),
Toussaint-Raven (1973), and Scott (1988). In this study the median contact area of the
lateral claws exceeded that of the medial claws by 69 percent. A previous report suggested
that the contact in the lateral claw of the rear hoof exceeds the medial claw by twenty to
fifty percent (Scott, I988). A possible explanation for this discrepancy involves the
stance of the subject during in vivo testing. If the cow adopted a base-wide stance during

testing, the metatarsus would not be perpendicular to the ground in the longitudinal

49

plane and therefore more contact would occur in the normally shorter medial claw. This
explanation supports previous reports on the biomechanics of the bovine hindlimb
(Toussaint-Raven, 1985) Bovine hindlimb lameness has been reported to occur more
frequently in the lateral digit (Wells, Trent, Marsh, McGovern, and Robinson, l993b; Smit
et al., 1986). The disparity of contact between medial and lateral claws in the present
study supports the chronic cyclic relative overloading theory as a risk factor for
development of digital disease. If, as suggested, chronic cyclic overloading is a
contributing factor for the development of digital disease, studies examining this
relationship would be beneficial. One potential method to examine this relationship would
be to utilize a prospective study similar to that previously described for the development
of lesions associated with subclinical lamintis. Repeated evaluation of the cattle at regular
intervals making observations of digital disease occurrence in the herd and analysis of the
results of the prospective study would determine if the sole load distribution was related to
the lesion distribution in the herd.

This study allowed the development of a standardized system for determining the
dorsal to plantar distribution of sole contact. Sole contact distribution zones in the present
study were created by dividing the length of each claw outline into three equal parts. This
division ensured that each zone contained one-third of the total claw length. Sole contact
information could then be collected flom each zone. Previous work resulted in the
development of a system of hoof zones, the Liverpool Standard, for describing the
location of lesions based on anatomic areas of the weight-bearing surface of the bovine

claw (Mortensen et al., 1992). In the present study, templates created from the Liverpool

50

standard zones could not consistently be used to create zones for sole contact distribution
because the shape of the sole did not always conform to the shape of the template. The
Liverpool standard template would have resulted in the loss of some sole contact
information from this study. The method of sole zone division used in this study could be
used for filture studies examining the dorsal to plantar distribution of sole contact in
hooves of varied shape. The information obtained using the present model provides a
more objective description of the dorsal to plantar distribution of sole contact in
abnormally shaped hooves than the results obtained using the Liverpool standard template.
The Liverpool standard template, however, provides medial to lateral or axial to abaxial
distribution information that the present method cannot provide.

The results of this study confirm that there is a statistically significant difference in
the sole contact between the zones of the claw. There were significant differences between
the dorsal and middle zones of the lateral claw, between the middle and plantar zones of
the lateral claw, between the dorsal and middle zones of the medial claw, and between the
dorsal and plantar zones of the medial claw (p< 0.05). The sole contact area of the lateral
claw is distributed in the dorsal and plantar zones. The observation of greater contact in
the dorsal and plantar zones of the lateral claw may support the cyclic overloading theory
for the development of pododermatitis circumscripta, toe ulcers, and sole abscesses as a
result of chronic subclinical laminitis (Greenough et al, 1981). Decreased contact in the
middle zone of the lateral claw may explain the researcher’s observation that the majority
of sole lesions occur either in the toe region (dorsal zone), or at the sole-heel junction

(plantar zone) of the lateral claw of the hind limb of cattle. The sole contact area of the

51

medial claw is distributed in the dorsal zone. The contact distribution results conflict with
the published literature, that suggests the majority of the contact under the soles of cattle
is distributed in the region of the heel and abaxial walls (Kasari, 1991). One explanation
relates to cow conformation and the position of the metatarsus during the mid-stance
phase. If a cow were sickle-hocked, i.e., possessing a tibiotarsal-metatarsal angle of less
than or equal to 130° (Greenough et al, 1981), the metatarsus would not be perpendicular
to the ground during mid-stance when viewed flom the lateral aspect. If the same cow
were cow-hooked or possessed a base-wide stance, the metatarsus would not be
perpendicular to the ground during mid-stance when viewed flom the rear (Greenough et
al, 1981). Either of the these conditions would alter the loading and possibly the sole
contact distribution of the hoof (Toussaint-Raven, 1985). Another explanation for this
difference is that the present study evaluated hooves of varied hoof conformation, normal
and overgrown, whereas Kasari (1991) discussed only overgrown hooves. In Kasari’s
report, the definition of hoof overgrowth and the method of determination of contact
distribution were not described. In the present study, the contact image represented mid-
stance contact and not contact associated with the entire ground contact phase, flom heel
strike to toe ofl‘. If the peak vertical forces or maximum sole surface contact during
locomotion do not occur when the metatarsus is perpendicular to the ground, as suggested
in the literature (Scott, 1988), the distribution of contact may actually be different. Studies
of contact distribution changes that occur as a firnction of locomotion are indicated. These
studies should include kinetic and kinematic evaluation of cattle with varied rear limb

conformation, taking care to assess hoof conformation and possibly block the results by

52

the hoof conformation parameter to attempt to control confounding of the limb
conformation data.

The typical location of the lesion of pododermatitis circumscripta is the plantar
zone of the lateral claw. Although no lesions of pododermatitis circumscripta were found
in the sample population, the median contact area of the LP zone was significantly higher
than the median contact area of the LM zone but was not significantly different than the
median contact area of the LD zone. A relatively large proportion of the contact occurs in
the LP sole zone. The theory that chronic relative overloading can be a major predisposing
factor in the development of pododermatitis circumscripta would be supported by these
findings. Further studies examining pressure distribution within the claw during
locomotion may be beneficial in exploring the potential etiologic factors associated with
lameness in cattle.

The distribution of claw contact was evaluated as sole contact area in cm2 and as
the percentage of the total claw contact area in each sole zone. While the sole contact area
in cm2 is important, large variations in sole contact areas made distribution evaluation
difficult. By using a percentage of the total claw sole contact, hooves with large variation
in sole contact area could be compared.

The hoof conformation parameters utilized included the toe height, heel height,
and the T:H. These easily measured parameters were chosen as a result of the personal
experience of the investigator as a professional hoof trimmer and the previous report of a
high correlation between the T:H and claw disorders resulting in lameness (Ral, I990).

The heel height measurement technique involved measurement of the heel height as the

53

height of the heel perpendicular to the ground measured at the junction of the abaxial
groove and the coronary band. This modification of the measurement technique previously
described (Vermunt and Greenough, I995) enabled use of an anatomic landmark (abaxial
groove) to decrease the variability associated with the heel height measurement as
described by Vermunt.

The conformation parameter with the highest correlation to the percentage of total
medial claw contact in zones was the medial claw toe height. None of the correlations
were of sufficient magnitude to allow meaningful regression analysis. This finding
indicates that other conformation parameters may have a higher correlation to the
distribution of sole contact than the measurements utilized in the present study. Future
studies should include the evaluation of other hoof measurement parameters, specifically
the dorsal wall angle, dorsal wall length, and claw or sole length based on the previous
heritability studies (Hahn et al., 1984; McDaniel, I994; Smit et al., I986; and
Baumgarter and Distl, I990).

The final portion of this study dealt with the predictive potential of hoof
measurement and contact distribution. Correlation analysis performed revealed only low
correlation (R<0.80) between the toe height, heel height or the T:H and the percentage of
total claw sole contact in each sole zone. With low correlations, regression analysis would
be of little value. If the correlation analysis revealed a stronger relationship (R>0.80)
between the variables the predictive potential would have been explored. Since the data

collected were not normally distributed (non-gaussian) the predictive potential of the

54

variables would have been evaluated with a non-parametric test. Chi-squared testing could
have been utilized after the independent variables were transformed to categorical values.

The low correlation between the contact distribution and external hoof
measurement parameters resulted in the rejection of the hypothesis in this experiment.
Increased toe height, decreased heel height, or an increased T:H does not appear to result
in a plantar redistribution of the sole contact. The distribution of sole contact cannot be
predicted using the selected external hoof measurement parameters.

Statistically, low correlation between contact in the sole zones selected for this
study and changes in the toe height, heel height, and T:H indicate that other evaluation
techniques may be better at distinguishing changes in contact or load distribution
associated with hoof conformation changes related to overgrowth or abnormal wear.
Other evaluations that could be performed include the utilization of a more sensitive
recording medium, selection of different hoof conformation parameters, such as the dorsal
wall angle or diagonal hoof length, and creation of different sole zones that would detect
differences in the contact distribution with greater sensitivity.

One potential explanation for the low predictive ability of this measurement
technique is that a number of factors are involved in the distribution of load on the hoof.
These factors may include sole surface area, sole depth, hardness or elasticity of the sole
matrix, and the sole contact surface. Certainly the musculoskeletal system can adapt to the
gradual changes in hoof conformation associated with hoof grth or wear. One
weakness of in vitro studies, is that soft tissues do not behave as they do during in vivo

evaluations. Future in vivo studies should examine changes in load or contact distribution

55

associated with trimming the hooves. These studies should also examine changes in sole
contact and load distribution in lame cattle.

Information on the contact area of the bovine digit was collected and analyzed
using commercially available products and software. The development of the technique of
collecting contact information with commercially available pressure-sensitive film would
enable firture studies involving in vivo testing to be performed in field situations. The film
could be incorporated into a cassette which could then be placed on a force platform in a
portable runway. Development of a system of this nature could lead to a relatively easy to
assemble and readily available portable biomechanics laboratory which could be utilized in
conducting research on gait analysis and lameness in cattle.

The use of a portable laboratory in bovine gait analysis studies would allow the
collection of data fiom a relatively large number of cattle at one site. By setting up the
laboratory on a farm, the entire herd could be tested without incurring the expense and
subject stress associated with transporting the herd to a central laboratory. On daily
operations the testing apparatus could be placed in the exit alley fi'om the parlor and data
could be collected with minimal disruption of the normal herd routine. The collection of
baseline data could be performed on normal cattle and compared to the data fiom lame
herdmates. This would allow identification of disturbances in gait associated with specific
conditions resulting in lameness. In herd lameness situations, repeated examination of
cattle would allow the identification of biomechanical changes associated with the
development of conditions associated with lameness. One specific application could be the

repeated evaluation of cattle at risk of developing lameness secondary to the occurrence of

56

subclinical laminitis. In filture studies the image analysis procedures outlined in this study
could easily be used to evaluate conformation changes associated with corrective hoof
trimming. A digital photograph could be recorded before and after corrective hoof
trimming was performed. These images could then be analyzed to determine differences in
the hoof measurement parameters obtained from the lateral or medial views of the hoof,
including toe height, heel height, dorsal wall angle, dorsal wall length, and diagonal claw
length. In addition to these parameters, a digitized photograph of the sole could easily be
evaluated to obtain claw length and width. The changes in hoof conformation could be
compared to the changes in loading and kinematic data to determine the quantitative effect

of hoof trimming on the gait and sole loading pattern of the subject.

CONCLUSIONS

Even though the hypothesis that increased toe height, decreased heel height, or an
increased T:H leads to a plantar redistribution of the sole contact was rejected, this study
led to several important findings. An in vitro method of load application and collection of
the contact distribution profile of the bovine hoof was developed. A method of computer-
assisted image analysis utilizing commercially available software was also developed.

The total sole contact area of the rear hoof on a flat smooth surface is
approximately 2.0 cm2. With sole contact areas this small, the forces applied to the sole
during weight-bearing become extremely large. These large forces may contribute to the
development of lameness. The provision of comfortable, appropriately sized, free-stalls or
loose housing rest areas should be a priority in herds with intensive housing. Comfortable
flee-stalls or loose housing areas may promote hoof health by resting the corium of the
sole. Corrective hoof trimming to increase the weight-bearing surface area should result in
dissipation of these large forces. If chronic cyclic overloading is a major contributor to
digital disease, increased production, reproductive efficiency, and decreased treatment
costs as a result of increased cow-comfort could be dramatic. The sole contact in the
lateral claw is greater than the sole contact in the medial claw. The majority of sole
contact of the lateral claw is distributed in the dorsal and plantar zones and the majority of
sole contact of the medial claw is in the dorsal zone.

57

58

In conclusion, this study confirms that there is a significant relationship between
toe height measurement and some of the sole contact distribution in the bovine hoof.
Based on the information obtained from this study changes in sole contact cannot be
predicted by measuring changes in the hoof conformation parameters toe height, heel
height or T:H. Further studies are indicated to examine the pressure distribution changes
on the sole in cattle as a result of corrective or routine hoof trimming. Additional studies
evaluating the sole contact, load distribution changes, and hoof conformation associated
with lameness in cattle are indicated. These studies would be beneficial to practitioners,

hoof care professionals, and producers interested in the prevention of lameness in cattle.

APPENDICES

Appendix A
Hoof Testing Protocol
Notes on Fuji Film
1.0 Select Superlow Pressure film.

2.0 Cut films to 5x7 in. Roll is 10 5/8" cut 7"piece flom roll and cut in half to achieve
two 5 5/16"x7”sections

3.0 Place “0” film on top of “a” film.

4.0 “c” film contains red pressure indicator, place dull surfaces together, mark corner
with fingernail to confirm red indicator.

5.0 Place film in sheet protector (14 cm x 22 cm) one halfof sheet protector.

Hoof

loss surface white

«c» VVVVVVVVVVVVVVVVV developer

”a” ooooooooooooooooooooooo

glossy surface (tan) dye

Wood Base

6.0 Load hoof with white glossy side up.

7.0 Scan with glossy side down.

59

60

Appendix B

 

use 500# load cell
Laboratory For Comparative Orthopaedic Research $111321; 1tg7lnstron
Hoof Testing Protocol Labtech2Hoofiest
Program

 

 

 

1. Start with actuator C e 40 mm

2. Place 14 cm x 21.5 cm tracing paper on testing platform.

3. Place hoof assembly on posts, making certain that bearings glide freely by moving up
and down. Before inserting locking pin, blow air through hole to remove metal filings or
debris.

4. Reset minimum load. Rezero with the hoof hanging.

5. Move actuator down while holding both digits above platform.

6. Preload to _=_ 70N (15 1b.); adjust actuator until adequate sole contact is achieved.

7. Position dorsal wall of each digit in contact with toe board. Tighten toe board with
wrench.

8. Trace hoof outline on paper and mark reference points (medial, lateral, plantar, axial,
and abaxial grooves).

9. Raise actuator, zero load cell and remove tracing paper.
10. Place Fuji film on testing platform.

11. Lower actuator while holding both digits above film, position dorsal walls against toe
board until sole contact is achieved.

12. Adjust preload to E 70 N (15 lb.) and visually inspect wall contact.
Position “Suppress Current” to zero displacement

61

f 13. Load to E 1300 N (3001b) using wave form settings of:

| POS’N Shape .400 0.25 I

| RAMPS s RAMP mm mm/sec]
at a displacement rate of 0.25 mm/ s and range of -25.0 mm.

 

 

 

 

 

 

14. Hit hold key to stop displacement at 1300 N ( load will drop), mark reference points
(medial, lateral, and plantar). Record minimum load (maximum compressive load)

15. Hold digits.

l6. Unload to 0 load (hit reset button) raise actuator to remove FUJI film without
touching or sliding hoof on film.

17. Save mechanical testing data.

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