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David Hall FdSc Dip,WCF Hons April 2013 1

MR3127BSc (Hons) Dissertation Farriery Science

A pilot study into specific metacarpal measurement

variants causing asymmetry and there relationship to

coronary band width between right and left equine fore

limbs in fifteen matched pairs of morbid specimens.

David A Hall Dip WCF (Hons) FdSc Student number: 20118021458571

Word Count: 10,034

Acknowledgements

I would like to thank the staff at Myerscough College for their tuition through out

the five years of this course. I would like to take this opportunity to also thank

Mark Caldwell for his friendship and guidance, and Loraine Allan for stepping in at

the last minute with her excellent style of teaching. I would like to acknowledge

my fellow students on this course for all pulling together and helping each other

when it got to hard, without the camaraderie it would not have been possible to

complete the course. For those that helped with computer skills and literacy along

the way and my family for there help and patience.


Abstract

Introduction

There is a lot of anecdotal evidence that links asymmetric limb length and miss

matched feet with performance and future pathology, little is known about the

individual elements that go to make up the asymmetry in the fore limb.

Study design

A quantitative experimental pilot study.

Hypothesis

Is there asymmetry in bone measurements taken from the third metacarpal between

right and left fore limbs of the same horse and is there a relationship with miss

matched feet.

Aim

Too test the hypothesis that there is a relationship between metacarpal length, width

and circumference with coronary band width.

Objective

To test the length and other measurements of the third metacarpal to see if there is

asymmetry in the bone, to measure coronary band width and see if there is a

relationship.

Materials and Method

In a pilot study of 15 matched pairs of fore limbs freshly amputated below the carpus

3 measurements of the third metacarpal were taken, the overall length of the bone,

the width of the bone at mid shaft and the circumference of the bone at mid shaft, to

determine if asymmetry existed in theses measurements. The coronary band width


was also measured to determine if the feet were mismatched. The bone

measurements were then compared to the coronary band width using computer

software (Microsoft Excel ® and Minitab 16®) to see if there was a correlation

between the two measurements.

Results

Asymmetry was found in the Mid shaft circumference of the third metacarpal in 14

out of 15 of the matched pairs of bones, 13 of the circumferences measured were

larger in the left limb than the right limb, and one pair was larger in the right limb than

the left limb. There was a strong correlation between coronary band width

differences in the miss matched feet and the circumference differences in the third

metacarpal. No significant difference was found in metacarpal length.

Conclusion

Horses with a wider coronary band will have an increase in circumference in the mid

shaft of the third metacarpal.

Significance

The study gives further weight to the theory that miss matched feet are linked to bio

mechanical function and in some cases handedness and any alteration of this

condition should take the horse as a whole into consideration.


Contents Page

Title page Page 1

Acknowledgements Page 2

Abstract Page 3

Table of contents

Chapter 1 – Rationale and introduction Page 8

1.1 Rationale Page 8

1.2 Introduction Page 8

1.3 Anatomy of the lower limb Page 10

Chapter 2 – Literature review Page 13

2.1 Introduction Page 13

2.2 Review Page 13

2.3 Asymmetry in the long bones Page 13

2.4 Asymmetry in the equine third metacarpal Page 14

2.5 The hoof capsule Page 16

2.6 Bio mechanics Page 18

2.7 Handedness Page 19


Chapter 3 – Methodology Page 21

3.1 Introduction to methodology Page 21

3.2 Aims of the study Page 21

3.3 Hypothesis Page 21

3.4 Experimental design Page 22

3.5 Ethical consent Page 22

3.6 Objectives of the research Page 22

3.7 Experimental procedure Page 25

3.8 Data collection Page 26

3.9 Data analysis Page 27

3.10 Procedural check list Page 27

Chapter 4 – Results Page 29

4.1 Group demography Page 29

4.2 Environmental standardisation Page 29

4.3 Discussion of results on raw data Page 30

4.4 Statistical analysis Page 31

4.5 Metacarpal Length Page 31

Chapter 5 – Discussion Page 36

5.1 Metacarpal Asymmetry Page 36

5.2 Coronary Band Width Page 36


5.3 Relationship between coronary band width and third metacarpal length Page 36

5.4 Limitation of Study Page 38

Chapter 6 – Conclusion and recommendations Page 38

Chapter 7 – Clinical relevance Page 39

7.1 Clinical relevance of the asymmetry Page 39

7.2 Asymmetry in the hoof shape Page 39

Reference List Page 40

Bibliography Page 43

Appendices Page 44


Chapter 1

Introduction and rationale

Rationale

A study by Watson (2003), the third metacarpal was measured by x-ray in the right

and left fore limb in thoroughbred race horses. The study showed differences in left

and right metacarpal length of between 5-9 mm in 50% of the horses measured.

Studies have indicated that a high frequency of asymmetry occurs in a random

population of horses, most notably in the height of the shoulder on the right limb

Wilson et al (2009), whilst Dollar (1898) has previously stated that the conformation

of the limbs depends on the varying lengths of the individual bones and upon the

angles they make with each other. This led the researcher to conduct this study into

bone asymmetry in morbid specimens. A proper understanding of asymmetry and its

causes will help clinicians develop a rational for treatment and an increase in the well

being of the horse.

Introduction 1.1

Much work has been done identifying the existence of asymmetry in equine front

limbs and feet. Studies have indicated that a high frequency of asymmetry occurs in

a random population of horses, most notably in the height of the shoulder on the

right limb (Wilson et al 2009), whilst Dollar (1898) has previously stated that the

conformation of the limbs depends on the varying lengths of the individual bones and

upon the angles they make with each other. In a study in Australia by Watson (2003)

the third metacarpal was measured by x-ray in the right and left fore limb in

thoroughbred race horses. The study showed differences in metacarpal length of

between 5-9 mm in 50% of the horses measured, with 80 % of the horses exhibiting


a greater or lesser difference than this. 20% of the horses had an equal length in the

metacarpals. 76% of the horses had a longer right metacarpal. In a study on race

horses in Australia by Decurnex (2009) the proximal hoof circumference was

measured on horses during training and rest periods. A decrease in circumference

was recorded during training and the circumference of the proximal border increased

whilst the horses were out of work and in the paddock, the largest increase being in

the right fore.

Asymmetry in the hoof capsule is easily observable but difficult to quantify although

work has been done using external reference points Duckett (1990). Hoof capsule

shape and size where left differs from right constitutes asymmetry. Redden (2003)

studied asymmetry in miss matched feet, the study graded hoof angles between 1-4,

where 1 is where the hoof angle is between 3°-5° greater than the opposing foot

which would be clearly observable as an asymmetry and grade 4 being the coronary

band being further forward of the bearing border at the toe. In a recent paper on hoof

volume by Caldwell et al (2012) it was established that in a displacement test

between right and left amputated morbid hoof capsules that the hoof with the lowest

volume had the narrowest coronary band width.

Gray (2007) reported handedness in horses could contribute to limb asymmetry, this

would be difficult to prove but it is possible to cross reference other aspects of

handedness reported in humans with the observable conditions in the equine, such

as hoof capsule such size and shape differences and limb length differences. In Cuk

(2001) a paper on long bone asymmetry it stated that humerus length is reflected in

handedness in humans. If there is any form of handedness in the equine then it

should be reflected in the third metacarpal.

In a recent pilot study Caldwell et al (2012), the existence of limb length disparity

was identified using external markers on given reference points of the horse. The

study showed that in this small study that 75% of the horses demonstrated fore limb

asymmetry.

1.2 Anatomy of the distal limb and the foot


The Third Metacarpal Bone

The third metacarpal bone is a typical long bone and is vertically orientated between

the carpus and the proximal phalanx, and is one of the strongest bones in the

skeleton. The dorsal surface is smooth, rounded from side to side and nearly straight

in length.

The palmer surface is flat from side to side. On either side is a roughened area for

the attachment of the second and fourth metacarpal bones. With the second and

fourth metacarpal bones the palmer surface of the third metacarpal forms a channel

for the passage of the suspensory ligament. The proximal extremity has an articular

surface for the distal row of carpal bones. On the dorso medial aspect is a

roughened projection, the metacarpal tuberosity, for the insertion of the tendon of the

extensor carpi radialis muscle. The distal extremity articulates with the proximal

phalanx and the proximal sesamoid bones. A sagittal ridge divides it into two

condyles, the medial being slightly larger. On either side there is a small depression

for the attachment of the collateral ligaments. . Hickman (1988)

During development of the bone in the embryo the bones are composed of Hyerline

cartilage, but by birth most of the cartilage forming the shaft of these bones has

ossified. After birth the extremities rapidly ossify to form the bony epiphyses. The

bony epiphyses are separated from the shaft by a layer of cartilage called epiphyseal

cartilage or growth plate. The bone grows in length by the proliferation of the

cartilage cells forming the growth plate and their replacement by bone. Uneven

growth of the growth plates results in angular limb deformity of the leg. . Hickman

(1988)

When bone reaches its maximum length proliferation of the cartilage cells stops and

the growth plates become completely ossified. The shaft of the bone and the

epiphyses are fused and the bone ceases to grow in length. The conformation of the

horse is established and cannot be altered. A long bone grows in overall thickness

by the deposition of the bone on the surface from the inner cellular layer of the

periosteum. At the same time the marrow cavity is enlarged by the reabsorption of

bone. Closure of the growth plates of the third metacarpal occur at one year with the

rapid growth of the bone occurring at 0-3 months. Hickman (1988)


Coronary Band Width

The coronary band is the area at the proximal aspect of the hoof capsule and

combines the production of the hoof wall from the coronary corium with a flexible

union between the dermis or horse’s skin and the hoof wall Stashak (1996). The

width of the coronary band will be affected by the distal phalanx and the attached

lateral cartilages and the angle they occupy within the hoof capsule. This will also be

affected by the structures above the capsule composed of bones, ligaments, tendons

and muscles. The flexible lateral cartilages are attached to the distal phalanx

medially and laterally extending palmarly past the last point of the wing of the distal

phalanx they give shape and form to the posterior of the capsule. They extend

proximally and are situated half in the capsule and half out. They can be palpated

just above the coronary band and situated between them between them is the digital

cushion which gives shape to the bulbs of the heels.

The hoof is designed to with stand the incredible static and dynamic forces to which

it is subjected. In Lungwitz (1908) he used closed electrical circuits to establish the

order of the capsule deformation, he established in a bare foot model that the heels

expand on ground impact as the caudal parts of the foot are loaded shown in fig 1.1.

The distal phalanx rotates caudally ventrally thus transmitting weight to the laminar

interface. The coronary band descends as the dorsal wall becomes concave and the

sole flattens. This is also reported by Roepstorff (2001).


Fig 1.1 A diagram of the hoof function under load, according to Lungwitz (1908)

Fig 1.2 shows a transverse section through the hoof capsule at the level of the

coronary band. It illustrates the structures present in the hoof which gives it shape

and is subjected static and dynamic forces placed on it.


Chapter 2

Literature Review

2.1 Introduction

The majority of available research into bone length asymmetry has been completed

in the human medical field necessitating the extrapolation of this into farriery and

equine context. The research methods used for this study included the internet,

veterinary publications such as Equine Vet Journal and university library. The

internet research utilised scientific paper specific search engines, science direct

Wiley on-line and Google scholar.

Key search words were limb disparity, asymmetry in equine and long bones.

Coronary band width, miss matched feet in the equine and handedness.

2.2 Literature review;

Human long bones, third metacarpals, hoof capsules, bio mechanics handedness.

2.3 Asymmetry in human long bones

Studies of the degree of asymmetry in human long bones began on the 19th century.

The most frequently used the dimensions were total length and weight measured

both in skeletons, in living people, and in archaeological collections. Although data

was gathered in different groups of people living in different circumstances all results

agree and demonstrate that bilateral asymmetry is more marked in arm bones than

the leg bones and that on average, right arm bones are longer by 1% - 3% and

heavier by 2% - 4% than the left arm bones Steele (2000).

Cuk (2001) carried out a study of the lateral asymmetry of the human long bones

based on anthropometric data of long bones of 26 female and 16 male medieval

skeletons. The results confirm the presence of orientated asymmetry more

prominent in the arms and legs. The average lateral asymmetry in the arms was

found in the right arm, and in the legs to the left leg. By far the most asymmetric

bone though was the humorous and almost all the parameters were highly significant

but particularly the circumference of the shaft, the width and the maximum length.


These findings reflected other studies on handedness. The dominant leg is

expressed by the stronger tibia usually on the opposite side of the dominant arm.

The stronger development of the left tibia as a supportive limb is characteristic of

both right and left handedness.

2.4 Asymmetry in equine third metacarpal.

In a short communication on third metacarpal bone length and skeletal asymmetry of

the racehorse by Watson (2003) the study set out to investigate the differing lengths

between left and right third metacarpal in the same horse. The aim of the study was

to establish whether there was a consistent difference in third metacarpal length in

two independent groups of thoroughbred racehorses. The study was done using

radiographic views lateromedial of the left third metacarpal and the mediolateral

radiographic view of the right metacarpal. The radiographs were then measured for

each horse using a plastic ruler in mm between the most distal point of the proximal

joint surface and the most proximal point of the distal condyles.

The sample size of 46 racehorses in two yards seems to be an adequate number for

the study. There was no mention of any exclusion criteria in the experiment and no

mention of ethical consent.

They were aged between 2-6 years and had raced or were in training at racing

speed at the time the radiographs were taken. The measurement process used an

interesting validation method of using the x-ray machine to compare the contra-

lateral measurements, as well as the lateral measurements and comparing the mean

of the two which should have taken into account any perspective inaccuracies. The

study used a paired t test adopting a significance level of P>0.05.

The study reported that 76% of the horses investigated had a longer right third

metacarpal with three of the right third metacarpals measuring more than 10 mm in

difference, and with 15 horses measuring between five and 9 mm difference with the

right being longer. These are indeed quite large differences, but this may be because

the differences are related to breed and usage, the horses being very young with soft

bones and being exposed to fast work on race courses that involve running on a

circular track. These results in figures reflect the humerus differences in the human

study of Cuk (2001)


Both papers have slightly different theories as to what causes asymmetry. Cuk et al

(2001) believes that human asymmetry in the upper body (humerous) and the lower

body (femur and tibia) come down to the forces exerted onto the limbs as well as

usage. However (Watson et al 2003) believes that asymmetry of the third metacarpal

is a result of growth process within an individual horse’s skeleton. Cuk et al (2001)

high lights that a factor of asymmetry may also be due to availability of minerals and

vitamins, as well as hormonal regulation, however their experiment concentrates on

forces applied to the limbs along with the usage of the limbs.

Other theories have a part to play in these papers. Steel & Mays (1995) and Cuk et

al (2001) acknowledge that asymmetry can be a result of growth and developing with

age, however in the sense that the older the human becomes, the more usage and

force applied to the limbs. Whereas the Watson et al (2003) paper included theories

that back up asymmetry forming through growth, Kandel et al (1991) reported that

there is asymmetry within the brain, which was proven in great apes, monkeys, cats,

rats and birds. Watson et al (2003) can then refer these results to the horse and

further relate them to the horse’s sidedness, which causes skeletal asymmetry. All of

this occurs without acknowledging extreme usage and forces exerted onto the

different limbs as also reported by Plato et al (1980). These theories are very

different, however both very possible. Cuk et al (2001) and Ruff & Jones (1981)

highlight that they believe that humans develop transverse asymmetry. This is

developed within humans and means that right handed people have a more

developed right arm and left leg, and the reverse in left handed people. Also within

the paper information is given about what Singh (1970); Plato et al (1985) ; Macho

(1991) have all agreed on, which is that the left leg is used as the supportive leg,

without any link too right or left handedness, which then means the right leg is used

for other uses such as kicking.

Cuk et al (2001) do not go into direct detail about how the human is affected by

asymmetry. However, Watson et al (2003) explains that asymmetry between the two

sides of the body may cause trouble with the horses coordination and balance, and

also could be the cause of unilateral injuries. Big asymmetric differences may affect

movement ability along with soundness within the racehorses and turning around the

track.


Both papers provide results which varied as well as highlighting areas of similarity.

Cuk et al (2001) found that within humans greater asymmetry is found in the upper

body than the lower body, because they found that the arms have a lot more uses.

Humans are also proven in the experiment to be transverse asymmetric, so they

found that right handed people are stronger in the upper half of the body in the right,

and stronger in the left leg for the lower half of the body, then the reverse for left

handed people, which agreed with other studies/theories carried out. However,

regardless to the human’s handedness, the left leg is considered the supportive leg

because it is heavier in the majority of humans and the right leg is used to other

functions. Watson et al (2003) found that the majority of horses (76%) had a longer

right third metacarpal, which was similar to the Meij & Meij (1980) study which

proved 25 out of 30 horses had a stronger hind left limb, which would indicate that

horses with a longer right third metacarpal would also be left hind limb dominant,

showing a connection between humans and horse asymmetry, that being transverse

asymmetry.

2.5 The hoof capsule

In a study by Wilson (2009) into skeletal forelimb measurements and hoof spread in

relation to asymmetry in the bilateral forelimbs of horses. The sample size of 34

leisure horses is an adequate size. No exclusion criteria were mentioned, and no

ethical consent criteria are listed in the paper. There objective was to investigate the

relationship between the morphometry of forelimb segments and hoof spread and

the incidence of asymmetry. 10 bilateral Morphometric measurements of the front

limb were taken four hoof traits and six limb traits were measured. The hoof

measurements were hoof width at the bottom, hoof width at the top, toe height and

heel height. The problem the researcher (Hall) decided with the measurements in

this paper of the hoof width at the bottom, the heel and toe height was it will be

affected by possible outside influences such as inaccurate farriery trimming or

uneven wear. In a pilot study by Caldwell (2012) these measurements were

discounted and the natural coronary band width (CBW) was selected as any

variance in CBW is likely to be bio mechanical influence similar to that of bone

morphology. Wilson’s paper reported no significant difference in the top hoof

measurement between left and right hoof capsules with a mean of 112.1 plus or

minus 11.5 mm in the left capsule and 112.5 plus or minus 11.2 in the right capsule,


although the range suggests some significant differences at the plus or minus range

between left and right. The limb measurements showed the largest difference with

the measurement at the point of shoulder showing an asymmetry index mean of

12.12mm a range of 0.67-38mm. The statistical test was chi-squared test (X²).

In a pilot study by Caldwell (2012) into hoof volume in the front feet of the horse

amputated at the coronary band, he established a formula for predicting hoof volume

by using the coronary band width. The sample size was 10 pairs of matched feet, so

more of a pilot study. The feet were trimmed to a protocol Caldwell (2010) and

various measurements of a freshly amputated hoof were recorded. The hoof was

then submersed into a displacement tank and the correct volume recorded. The

measurements from the hoof and the known volume calculations were then

processed in mini tab using stepwise regression and a formula that predicted the

volume of the feet was produced. The computer programme picked coronary band

width as the measurement to be multiplied by a constant and divided by a coefficient.

In a study by Decurnex (2009) into different exercise regimes on the proximal hoof

circumference in young thoroughbred horses the author records the decrease in the

circumference of the coronary band as the horse is in training and an increase in

circumference while at rest. The author sites as do many the reason for performing

the study most lameness in horses relates to foot problems and may be associated

with changes in hoof shape, but a lack of information on the influence of normal

exercise on hoof shape. The study was on thirty seven young thoroughbred race

horses, the study lasted sixteen months, thirty two horses managed two consecutive

training periods at the stable separated by a period of rest in a paddock. Five horses

did not complete the second training period. The foot circumference was measured

just below the coronary band weekly with a measuring tape. The study was designed

to test whether proximal hoof circumference was influenced by the type of exercise

accomplished by the horse (gallop training versus rest in the paddock). A one

sample t test was used to evaluate if the mean change per week (during the training

periods as well as during the rest periods) differed from zero. Paired t tests were

used to compare the changes in circumference between the first training period and

the resting period and the change in circumference between first and second training

periods. Most horses showed a similar pattern of change. Decurnex doesn’t really

have an explanation for his findings but does record that the circumference was


often bigger on the right, the conclusions the researcher draws from this is there is

an inherent asymmetry in these measurements.

2.6 Bio mechanics

In a study by Van Heel (2006) into uneven feet within foals, this may develop as a

consequence of lateral grazing behaviour induced by conformational traits while

foraging. The author of the study questions whether the associated asymmetry will

be linked in the future to loss of performance, injury and future pathology. The study

was on twenty four Warmblood foals born and raised at the same location. There is

no exclusion criteria mentioned in the study and no ethical consent was mentioned.

The foals were visited once a week for an eight hour period by two persons, the

group of twenty four were divided into two groups of twelve and assigned to each

student. The foals were recorded for ten minutes in the hour by scanning the group

and the stance preference if any recorded.

A single tailed t test and regression analysis was used to find that 46% of the foals

developed a significant preference to protract the same limb while grazing which

resulted in uneven feet and subsequently uneven load patterns, with the foot placed

in front having the lowest angle. Foals with long legs and small heads were

predisposed to develop laterality and therefore indirectly cause uneven feet.

In a paper by Scott (2004) Asymmetric limb loading with true or simulated leg length

differences on humans. It is interesting to compare the research on the human leg

length asymmetry with that of the equine, although the research may be different for

the human biped as opposed to the equine which is a quadruped. The paper states

that unequal leg length results in asymmetric limb loading. There is strong evidence

that suggests that musculoskeletal problems of the lower limb and back are

associated with leg length discrepancy. It states that equalising leg lengths to reduce

the incidence of musculoskeletal damage may be warranted, but there are different

opinions regarding the amount of discrepancy that induces abnormal loading and

there is conflicting evidence as to whether the long or the short limb sustains the

greater load, this question of which leg sustains the largest load is present in

debates between clinicians about horses.


The paper classifies leg length discrepancies as mild (3cm) moderate as (3-6cm)

and severe as more than (6cm), this is indeed extreme compared to the equine

quadruped. The experiment was to calculate symmetry indices from forces seen

during walking on a treadmill between subjects with mild limb length discrepancies

(true leg length discrepancy) and those with a raised shoe, (simulated leg length

discrepancy). There were 8 subjects in the true leg length group and 12 subjects in

the simulated group. All participants signed an ethical consent form that had been

approved by a human subjects institutional review board. Participants were screened

via questionnaire and excluded from the study if they had a history of orthopaedic or

neuromuscular problems other than a leg length discrepancy that might alter their

gait. The results for both the true and simulated leg length achieved by walking on a

treadmill with force plates imbedded showed that all four symmetry indices were

negative denoting higher values for the shorter limb. It states that mechanically

greater loading of the shorter limb would be expected. In transition from stance on

the longer to the shorter limb, the step down distance would be greater than from the

shorter to the longer limb. The peak push off force was greater for the longer leg as

to be expected as it carry the greater lever arm.

2.7 Handedness

In a study by McManus (2009) about the history of human handedness, he states

that about 90% of people are right-handed and 10% are left handed. And that

handedness is associated with functional lateralization for cerebral dominance, and

may also be associated with various types of psychopathology. Broadly speaking,

the vast majority of humans seem to have been right-handed since the emergence of

the genus Homo, some three to four million years ago. Likewise, in all societies

studied, there is a large excess of right-handedness. However, there have been few

studies exploring the detailed history of handedness, not least because adequate

pre-twentieth-century historical data are difficult to find, and very large sample sizes

with consistent measurement methods are required for studies. It is probable that

about 8% to 10% of the population has been left-handed for at least the past

200,000 years or more. Detailed data only began to become available for those born

in the nineteenth century, McManus (2009).


In a study by Gray (1989) he describes handedness in the equine and compares it to

the humans, outwardly, humans as well as horses tend to appear symmetrical with

respect to left and right, but function is not always symmetrical, especially during

certain phases of movement Steele (2000). This is the result of handedness, an

asymmetrical phenomenon of the brain. The most striking and most fundamental

manifestation of external asymmetry, handedness, is directly linked to brain

lateralization and is described as the "physical manifestation of brain laterality."

He states that the "split" or "dual hemisphere" type of brain is a characteristic

common to vertebrates. The left and right hemispheres interact and work together to

handle the complex tasks of analyzing and organizing thought processes and

directing physical activities and body functions. Laterality or Lateralization is the

neuropsychological term used to describe the division of labour between the two

brain halves of what is commonly referred to as the "split brain."Diagonal orientation

and handedness in the case of horse’s sidedness, resulting in lateralisation help to

understand the asymmetrical behaviour of horses. The study observed over five

hundred horses and his preliminary findings were that approximately 75% of the

animals studied displayed a preference for the left lead, which would indicate a

dominant diagonal consisting of the right hind/left fore (right sided). The number of

animals that displayed extreme ambidextrous tendencies was 3, less than 1%. The

number of animals showing sided tendencies, to such a degree, that one or more

limbs were showing obvious but tolerable signs of stress from weight bearing

imbalances was over 60%. Methods used to bring about improved locomotive and

weight-bearing balance included shoeing techniques which considered natural

asymmetrical tendencies, balanced riding techniques and therapeutic exercise.

These observations were not presented in a scientific format but were in accordance

with other authors and a pilot study by Caldwell (2012). Gray subscribes to the

theory that horses are inherently asymmetric and this wasn’t acquired, the horse was

actually born with theses tendencies.


Chapter 3 methodology

3.1 Introduction

This chapter sets out to describe the research methodology and design. Research

methodology is defined in simple terms as being a system of models, procedures

and techniques, which are used to find the results of a particular research problem

Panneerselvam (2004). Research techniques can be categorised into two sections

quantitative and qualitative or both can be used in mixed research methods Gray

(2010).

It has been described that quantitative research deals with quantity or numbers

whereas qualitative research, with quality and description of the subject being

researched, this summary however, is simplistic and distinguishing between the

paradigms can be problematic Parahoo (2006).

3.2 Aims of the study

The aim of this pilot study of a group of freshly amputated limbs was to record the

physical measurements of the length of the third metacarpal from the proximal

extremity at the point where the facet in the joint for the 4 th and 5th carpal bones sit

and at the distal extremity of the sagittal ridge at the lowest point of its radius.

Measurements of the mid shaft circumference and the mid shaft width were also

taken and recorded. The coronary band width was measured to see if there is a

correlation between the third metacarpal dimensions and coronary band width.

.

3.3 Hypothesis

There is a considerable volume of anecdotal evidence to suggest that miss matched

feet are linked to differential leg length syndrome (DLLS) and that DDSL is common

in domesticated horses, other terms for this condition are limb length disparity, odd

or uneven limb length.

There are differences between left and right coronary band widths, but there is no

difference in right and left metacarpal length, width or circumference. Therefore

differential leg length syndrome (DLLS) can not be linked to mismatched feet.


3.4 Experimental design

To establish if differences between left and right coronary band widths exist and if

there is a correlation between coronary band width differences and differences in

either length or circumference or width of the third metacarpal

We hypothesise that differences between left and right coronary band width exists,

but that there is no difference in right and left metacarpal length or circumference

therefore DLLS can not be linked to mismatched feet.

The experiment on 15 pairs of freshly amputated front limbs from 15 horses

euthanized for other reasons at a hunt kennels. The limbs were removed at the

carpus soon after death and stored in a cooler at two degrees centigrade until

sufficient limbs for the experiment had been gathered. The legs were examined to

make sure that they were free of damage from the euthanasia process, in all the

horses used in this experiment shooting was the method used to destroy the animal,

and not damaged in the amputation process. If any damage was encountered that

would affect the measurement process then they were excluded from the study. The

experiment was conducted on the hunt premises as moving the limbs would require

a licence.

3.5 Ethical consideration

Ethical consent was sought and granted from Myerscough college ethics committee

to conduct the experiment. The experiment met the strict guidelines set out by the

licensing laws for the movement and control of fallen stock, the amputated limbs fell

into this criteria. The experiment was to be carried out on a licensed premises with

written consent from the senior huntsman at the kennels and the limbs to be

disposed of immediately afterwards through the hunts disposal methods. Client

confidentiality was a major consideration, as the destruction of someone’s horse is a

sensitive matter. All data was stored on a computer hard drive with password

security.

3.6 objectives of the research

The objective of this research is to provide quantitative measurements that show the

possible components that make up the asymmetry or limb length disparity in the fore


limbs of the front legs of the horse. The other objective is to see if there is a link with

the observable asymmetry in the fore feet where the coronary band is narrower in

one foot compared to the contra lateral foot. The foot is a complex shape and

doesn’t fit any particular geometric shape. The nearest shape it comes to is an

incomplete cone.

There are many areas that one hoof can be directly compared to another and

measurements of all areas could be considered as comparative.

Establishing measurements that are not effected by outside influences will be

desirable Turner (1992). Influences that may effect will be farriery, the removal of

horn through trimming or burning. Farrier protocols have an inherent inaccuracy. For

example if the heel height differences were to be considered, one heel being higher

in one foot than the other, is this a result of inaccurate farriery or a morphology of the

capsule. In a study by Caldwell (2010) a trimming protocol was designed, but when

measuring for differences between feet the farrier will have an influence on these.

When visually assessing feet, the appearance of a difference in width at the proximal

aspect of the hoof can be observed. This observable capsule distortion is usually in

conjunction with other easily observable other factors within the limb this includes

high and low heels Van Heel (2006), Ridgway (2010), difference in distal radius

height Caldwell et al (2010) and position differences in the scapular position Buff et

al (2008)

In a pilot study by Caldwell et al (2012), the distal radius height was measured using

a laser level and a comparison done between left and right fore limb. While

performing this study the coronary band width was recorded. In 75% of those

measured there was a difference in radial height, where the distal radius was higher

the coronary band width was narrower. Where the distal radius was lower then the

coronary band was wider.

The coronary band was measured using an Invictor calliper in this experiment at the

widest part of the proximal capsule 10mm below the hairline on both fore feet.

The differences in measurement between the coronary band widths were not great.

The shape however of the proximal border was elongated and made easier to

observe.


Fig 3.2 This photo shows the experiment being under taken using the laser level.

By conducting this experiment it established that the position of the distal radius was

often at a different height in left and right.

The factors that could cause this would be a longer limb, a more obtuse angle in the

scapular humerous joint Buff et al (2008), an increased palmer angle Clayton (1990)

and shortening of the deep digital flexor tendon Redden (2003) or a longer third

metacarpal Watson (2003), or a combination of all three and other yet unexplored

factors. This was the reason for measuring the length of the third metacarpal.


Fig 3.1 Distal radius height is pin pointed by a laser level, by highlighting this anatomical feature, limb length asymmetry is then easily observed.

To measure the third metacarpal it was decided to measure from the dorso proximal

point between the joint facet of the 4 th and 5th carpal bones to the most distal point of

the median ridge. This will effectively be the longest measurement of the long bone.

3.7 Experimental procedure

The amputated limbs were examined for damage sustained in the euthanasia or

amputation, fifteen pairs were accepted and eight pairs were rejected because of

joint surface damage during the amputation or dissection process. The coronary

band width was measured using an Invictor calliper at the widest part of the hoof

10mms below the coronary band. This measurement was alternated between left

and right feet and repeated three times. Each of the measurements was verified by

operator and an assistant and recorded in a note book for transference to a table

later.

The limb was then dissected removing the third metacarpal in its entirety including

the second and fourth metacarpals still attached. Any parts of the limb below the

meta-carpo phalangeal joint, that included the proximal and the middle phalanx and

the hoof capsule which were discarded at this point. Owing to ossification of the

interosseous ligament between the second and fourth metacarpals to the large

metacarpal separation of these bones was very difficult without damaging the bones;

this is common in mature horses. It was decided to measure the shaft region with

them still attached.

The third metacarpal was measured using an Invictor calliper from the dorso

proximal point between the joint facet of the 4 th and 5th carpal bones as in fig3.3 to

the most distal point of the median ridge.


Fig 3.3

These measurements were verified by the operator and assistant, collected and

recorded in a note book for transference to a table at a later date.

The third metacarpal mid shaft width was calculated by dividing the overall length in

half and a mark placed on the bone with a permanent marker equidistant from the

proximal and distal extremities. This width measurement was taken from the medial

to the lateral extremities at this mid point using an Invictor calliper. Each

measurement was taken three times by the operator and verified by an assistant and

entered into a note book.

The third metacarpal mid shaft circumference was measured using a tailors tape at

the mark defined as the middle of the shaft equidistant from either extremity. Again

all measurements were recorded three times and verified by an assistant.

3.8 Data collection

Forty five figures were recorded for each measurement (15 pairs of limbs each

measurement measured three times) for both the left and right third metacarpals and

left and right coronary band widths. In order to standardise the measurements the

mean for the three measurements was calculated and entered into a Microsoft excel

spread sheet. The table consisted of 15 measurements for left metacarpal length

and fifteen for the right, fifteen measurements for the left metacarpal width and


fifteen for the right and fifteen measurements for the metacarpal mid shaft

circumference left and right. The left and right coronary band measurements fifteen

of each were also entered into the excel chart.

3.9 Data analysis

Statistical analysis is required to standardise the raw data, for this a student’s paired

t test is used, for this the number of points in each data set must be the same, and

they must be organized in pairs, in which there is a definite relationship between

each pair of data points. The coloration between the data set is calculated using a

Pearson's correlation coefficient. If it is believed that there is a linear relationship

between two quantitative variables with a change in one variable being associated

with a change in the other then Pearson’s correlation is used. The degree of

association is calculated Pearson’s product moment correlation coefficient can take

any value between -1 and +1 and expressed as r. It is said that there is a perfect

correlation if all the points lie on the line (XY) the value of the coefficient takes one of

its extreme values, either +1or-1. In order to establish a relationship we have a

positive correlation if the sign of the correlation is positive; then there is a direct

relationship between two variables so that as one variable increases in value so

does the other variable. If r has a negative correlation if the sign is of the correlation

is negative; then there is an inverse relationship between the two variables so that as

one variable increases in value, the value of the other decreases. To relate this to

our experiment if the probability value is p> 0.05 and r= 0.8 or above then it would

suggest there is a positive correlation between the two sets of data.

3.10 Procedural check list

1) The freshly amputated limbs will be skinned using a boning knife and the third

metacarpal removed in both left and right front limbs.

2) Using a sliding calliper the third metacarpal is measured in length from the

point on the most proximal dorsal facet as in fig 9 to the longest point on the

Median Ridge as in fig 10. Further measurements will be taken from the same


point on the Carpus to the extremity of the medial condoyle and then to the

same point on the lateral condoyle.

3) The mid shaft position is determined by dividing the length in half and a

permanent marker used to mark this point.

4) The width of the M3 will be measured medially-laterally at the mid shaft also

using a sliding calliper at the point marked.

5) The circumference of the third metacarpal is measured using a tailors tape at

mid shaft.

6) The measurements will be recorded in table form for later analysis and left

compared to right for differences.

7) The hoof capsule will be measured using a sliding calliper 10mm below the

hair line at the widest part of the hoof fig 11.

8) The hoof capsule measurements will be recorded in table form and left

compared to right.

9) Using data analysis the incidence of asymmetry in the right and left third

metacarpal will be ascertained and then compared by statistical analysis to

the asymmetry between left and right fore feet coronary band width to see if

there is a relationship.

Ethical consent

Ethical permission was sort to conduct this experiment. It was required

because the handling and moving of the morbid specimens is a licensed

operation.

The study did not identify the components that contribute to the asymmetry but

identified that it existed. As previously stated in Dollar (1898) that bone length and

the angles that they make with each other that a new study where matched bones

from morbid specimens could be measured this theory could be checked.


Chapter 4 - Results

4.1 group demography

The study sample consisted of 15 pairs of limbs amputated below the carpus joint.

The horses were of a mature but mixed age, size and type. No descriptive data was

recorded for the horses prior to being euthanized.

4.2Table of results of raw data

Key: CBW- Coronary Band Width; MCL- Metacarpal Length; MCW- Metacarpal Width;

MMSC- Metacarpal Mid-Shaft Circumference

Horses 1-15

CBW (mm) (Left)

CBW (mm) (Right)

MCL (mm) (Left)

MCL (mm) (Right)

MCW (mm) (Left)

MCW (mm) (Right)

MMSC (mm) (Left)

MMSC (mm) (Right)

Horse 1 116 115 272 272 43 43 127 125.5Horse 2 115 115 258 258 39 39 118 112.7Horse 3 129 129 259.3 260 44 44.7 126.3 126.3Horse 4 115 114 286.3 286.7 41 40 125 123.7Horse 5 114 115 280 278 40 39 120.3 119Horse 6 108 104 281 279 37 37.17 105 107Horse 7 111 105 279.3 279 42.17 41 118.3 116Horse 8 117 121 281 279.7 40.83 40 118 116.7Horse 9 107 102 278 277 41.3 39.7 117.7 115Horse 10 112 110 281.3 280 41 40 117.7 116.7Horse 11 110 108 287.3 286.3 39 39 114.3 113Horse 12 112 113 253.7 253 40.3 38.3 117 112.7Horse 13 135 136 280 277.7 46.3 46.7 134.7 134.3Horse 14 111 113 274 275 38 39 120 117.3Horse 15 106 105 256.7 255.3 36 35 111.7 110.3

Table 4.1 – Full results of all the horses studied.


MEAN LEFT (mm)

MEAN RIGHT (MM)

PAIRED "T" P value

CBW (mm) 114 ± 7.9 114 ± 9. p>0.05MCL (mm) 274 ± 11.3 273 ± 11 p>0.05MCW (mm) 41 ± 2.7 40 ± 2.9 p>0.05MMSC (mm) 119 ± 7 118 ± 7 p>0.05

Table 4.2 research descriptive statistics. There are no

significant differences between left and right limb variables

p>0.05

4.3 discussion of results on raw data

Metacarpal length was longer in left limb in 10 (67%) of the

limbs measured, 3 (20%) in the right and equal in 2 (13%).

The differences were very small and deemed not significant

when viewed as a percentage of the whole length.

Metacarpal width was wider in the left limb in 8 (53%) of the

limbs measured, 4 (27%) in the right and equal in 3 (20%).

Metacarpal mid shaft circumference was greater in the left

limb measured in 13 (86%) of the limbs measured, 1 (7%)

in the right and equal in 1 (7%). As mentioned before the

result’s shows a small difference in metacarpal length this

would be in accordance with the researcher’s previous

studies. The mean of the left third metacarpal length being

274mm+/-11.3mm and the mean of the right third

metacarpal being 273mm+/-11mm p>0.05.The asymmetry

in the third metacarpal length does exist but in small

proportions. There is a greater degree of asymmetry in the

width and circumference of the third metacarpal although


still small. The third metacarpal width at the mid shaft of the

long bone on the left had a mean of 41mm +/-2.7mm and

on the right 40mm +/- 2.9mm p> 0.05. The mean for the

mid shaft circumference on the left 119mm +/-7mm and on

the right 118 mm +/- 7mm.

The coronary band for the left hoof capsule was wider in 8

(53%) of the limbs measured, 5 (33%) in the right and equal

2 (13%). The coronary band width had a mean of 114 mm

+/- 7.9 mm on the left and 114 mm +/- 9 mm 0n the left.

4.4 statistical analysis of data

All the measurements coronary band width, metacarpal

length metacarpal width and metacarpal circumference

were transferred to Microsoft excel 2010® for statistical

analysis. Descriptive data were generated using analysis

tool pack Visual Basis for Application VBA. Pictorial

analysis of correlations was performed using scatter graphs

generated within excel graphs manager® with trends and

standard error and or deviations added using layout tools

within the data analysis software. Relationships were tested

using fielders “F” test for equal variance followed by two

sided student t test with either equal or unequal variances

as appropriate and at confidence intervals of 0.95. The

researcher then used paired t test, and Correlations were

calculated using Pearson’s correlation and tables of critical

values at N-2 DF (degrees of freedom) to determine if there

was a relationship between any of the three bone

measurements with the coronary band width.

4.5 metacarpal length

There was no difference in the length of the third

metacarpal, statistically no difference using the paired t

test. Using the Pearson correlation test there was no


correlation found with coronary band width and metacarpal

length. R=0.717 p>-0.102 for the right limb and a minus p

value for the left R =0.876 p-0.044.

4.6 metacarpal width

In the paired t test there was no significant difference

between third metacarpal width in left or right fore limbs.

n Mean(mm) St Dev

CBW(Left) 15 114.53 7.87

CBW(Right) 15 113.67 9.33

difference 15 0.867 2.669

Table 4.3 shows the mean, standard deviation and

standard error for CBW.

There is a 95% confidence interval for a mean difference:

(-0.611,2.345)

T-test of mean difference= 0 (vs not = 0) : T-value = 1.26 P

value = 0.229

There was a strong relationship with third metacarpal width

and coronary band width when compared in a Pearson

correlation test. R=0.819 p>0.05 for the left and R=0.784

p>0.05 for the right.

4.7 metacarpal mid shaft circumference

There was more significant difference between third

metacarpal mid shaft circumference in a paired t test

between left and right forelimbs.


N Mean (MM) St Dev (MM)

MMSC (Left) 15 119.40 6.98

MMSC

(Right)

15 117.75 7.08

Difference 15 1.653 1.723

Table 4.4 shows the mean, standard deviation and

standard error for Metacarpal Mid-Shaft Circumference.

There is a 95% confidence interval for the mean difference:

(0.669, 2.608)

T-test of mean difference = 0 (vs not =0) : T-value = 3.72 P-

value = 0.02.

There was a strong relationship with third metacarpal mid

shaft circumference with coronary band width in a Pearson

correlation test. R=0.089 p>0.05 with the left limb and

R=0.811 p0.05 for the right.

There is a strong statistical relationship between coronary

band width, and metacarpal mid shaft circumference and

third metacarpal width. This would be expected as when

the width increases it would be expected to show an

increase in circumference.

When the means between the four measurements

(metacarpal length, metacarpal width, metacarpal mid

centre circumference and coronary band width) are

compared they all show a larger mean for the left fore limb

than the right. This is comparative with other studies

performed.

We have already shown a significant linear relationship

between metacarpal mid shaft circumference and coronary


band width r = 0.81 p = 0.044. Metacarpal mid shaft

circumference was greater in the left limb measured in 13

(86%) of our sample pairs. We could not find evidence of

sufficient strength to suggest correlations between any of

the variables in our sample.

Accordingly at this time we must reject the null hypothesis

of a significant difference existing between key measures of

left and right metacarpal. We find we are also unable to

accept the hypothesis of no difference of key left / right

variables at this time without speculating as to the causes,

further work is needed.

A power calculation subsequently run in Minitab 16®

suggests that an increase in sample size in the magnitude

of 50 would give a CI in the region of 0.95.

0.00

50.00

100.00

150.00

200.00

250.00

300.00

Mean

LEFT

RIG

HT M

EASU

REM

ENT

(MM

)

Figure 4.1 highlights the difference between left and right variables, including the error bars and the standard deviation bar. There are no significant differences p>0.05.


100 105 110 115 120 125 130 135 14090

95

100

105

110

115

120

125

130

135

140

R² = 0.658933342327553

CBWLinear (CBW)

CBW (mm)

MM

SC (m

m)

fig 2

Figure 4.2 this scatter graph illustrates the strong correlation found between the

coronary band width and metacarpal circumference r=0.812 p=0.044. R has been

squared to normalise the distribution.

100 105 110 115 120 125 130 135 1409095

100105110115120125130135140

MMSC Line Fit Plot

CBWPredicted CBW

MMSC (mm)

CBW

fig 3

Figure 4.3 fitted line plot highlights the correlation between MMSC and CBW. The

data shows a strong linear relationship p<0.05

R=0.812

P=0.044


0 2 4 6 8 10 120

2

4

6

8

10

12

MMSC L - R CBW L - R

limb pairs ranked bt difference L-R.

coro

nary

ban

d w

idth

& m

etac

arpl

e cir

cum

fera

nce

Left

- Rig

ht d

iffer

ence

Figure 4.4 this scatter graph demonstrates a strong relationship between coronary

band width and Metacarpal circumference.

Chapter 5 discussion

Metacarpal asymmetry 5.1

The asymmetry that exists in the third metacarpal is less present in bone length and

more pronounced in mid shaft circumference and mid shaft width, although the width

as stated earlier will be related to an increase in circumference.

These findings match the anthropology studies Cuk (2001) of the femur of the

medieval skeletons. In that study the author finds that the largest asymmetry in

length of the long bone occurs in the right humerous of the human, it states that the

reason for that is the multi-directional function of the arm. The equine does not have

that range of movement in the fore leg that is present the upper arm of the human. It

is more in keeping with the femur of the human and as Cuk (2001) reports the same

increase in width and circumference and minimal difference in length as the

researcher has found in the third metacarpal.


Coronary band width 5.2

The differences in coronary band widths were smaller in this study than the

researcher has experienced in previous studies although still different. Previous

studies have been on live horses still weight bearing on the capsules being

measured. In the study performed in coronary band circumference on Australian

race horse horses Decurnex (2009) reported of the fluctuation in circumference

increasing while the horse is in training and decreasing while the horse is at grass. In

the time between euthanasia, amputation and measurement it may be while

unloaded the coronary band width contracts on the wider foot in the researcher’s

morbid specimens.

5.3 Relationship between coronary band width and third metacarpal length.

There is a strong statistical relationship between coronary band width, metacarpal

mid shaft circumference, third metacarpal width and metacarpal length. When the

means between the four measurements are compared they all show a larger mean

for the left fore limb than the right. This is comparative with other studies performed.

These results are not confined to the equine only they are reflective of results in

humans as well Cuk (2001). The results are similar to handedness and preferred

lead studies carried out Van Heel (2006), Gray (1989). The increase in bone

measurements like that of the coronary band likely to be larger because of increased

pressure from descending body weight more pronounced on one side (the left). In a

previous study by Hall (2010) on distal radius height the distal radius height

measured higher on the right limb in 75% of the horses measured, this linked to this

study may suggest a step down effect reported in White (2004) This would cause

increase in pressure likely to cause an increase in coronary band width and increase

in bone density.

It can be suggested that the measurement differences are small as larger differences

would interfere with the bio-mechanical functions of the quadruped. The visible

differences reported Dollar (1898) in limb asymmetry is likely to be the angle the

bones make with each other rather than length.


The existence of front limb asymmetry in various forms is not in dispute. In a recent

pilot by Caldwell (2012) it was identified limb length disparity existed. Using external

markers on given reference points of the horse, Weller (2006) the horse was

photographed. Using computer analysis the distance between the markers and the

angles were recorded and compared between right and left side of the horse. The

study showed that in the small study that 75% of the horses demonstrated fore limb

asymmetry. The study did not identify the components that contribute to the

asymmetry but identified that it existed. As previously stated in Dollar (1898) that

bone length and the angles that they make with each other that a new study where

matched bones from morbid specimens could be measured this theory could be

checked.

Fig 5.1 These images show external

reference markers placed on a horse and computer analysis to plot the distance and

angles to demonstrate asymmetry.

5.4 Limitations of the study

The lack of available research prior to this study makes it difficult to compare the

findings or how the experiments were performed. The fact the data was recorded on

cadaver limbs makes it difficult to compare the findings against the live equine.

Although it could be suggested that radiographs of the third metacarpal would

provide a linear measurement of asymmetry providing there was suitable calibration

for measurement. Measurements which are taken using an invicta calliper leave the


results open to individual bias or interpretation, which is why it is vital that external

researchers sample the data to ensure accuracy. A possible suggestion to overcome

this would be to photograph the bones and hooves and measure the linear lengths

and widths using digital measurement software providing there is suitable calibration.

Chapter 6 Conclusion

There were small differences measured in the length of the third metacarpal between

right and left bones. In this sample size the differences were not deemed as

statistically significant. However in a larger sample size it may be the small

differences have more significance, so it is not possible to say there is a relationship

between coronary band width and metacarpal length.

There is however a strong statistical relationship between third metacarpal

circumference and coronary band width, this would suggest that the asymmetry is

linked to bio mechanical forces on the limb similar to skeletal changes linked to

handedness.

Chapter 7 clinical relevance

7.1 Clinical relevance of the asymmetry

There has been much speculation on the existence of limb length disparity, unequal

leg length and differential leg syndrome and it is easily observed when viewing the

fore limbs in the equine. Much is spoken by the people involved in the performance

criteria of the horses and the consequences of an asymmetric horse as to whether it

is performance inhibiting and indeed if on pre purchase examinations from the

veterinary surgeons should the difference be treated as an unsoundness. Without full

knowledge of the constituents that go to make up the asymmetry and there links to

equine biomechanical lameness, Rooney (1968) then deciding if the condition is

linked with future pathology would be difficult.

With the discovery that the bone length of the third metacarpals, are not significantly

different then the asymmetry lies elsewhere, this may mean that different types of

asymmetry will be acquired or cured depending on environmental conditions

management and equine well being. This will explain that the appearance of some

types of asymmetry within the fore limb seeming to worsen or improve. Had it been


linked to unequal bone length then this fluctuation would be less likely to be

observed.

7.2 Asymmetry in the hoof shape

The researcher has concluded that the difference in hoof shape is reflective of

weight bearing pressure and handedness. The hoof, as stated before, on the

narrower coronary band width and elongated proximal shape has other

commonalities that lead the researcher to this conclusion. The measurements of the

coronary band width has a strong relationship with metacarpal circumference, in

studies previous to this pilot study the increase in long bone development is

suggestive of repetitive increase in load as would the deformation of the hoof

capsule, the increase in coronary band width being related to increase in metacarpal

circumference as in the Wilson (2009). The associated structures that would either

be related or the cause of the differing coronary band width would be the angle that

P3 occupies within the hoof capsule, Redden (2003), Moleman (2005) and the

contracture of the flexor tendons and or contracture of the muscles involved in there

operation Redden (2010)

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Appendices letter of consent from the hunt kennels for carrying out the experiment

on there premises.


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