hip dysplasia research

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HIP ASSESSMENT FOR DYSPLASIA DURING PRE AND POST

SKELETAL MATURITY IN GERMAN SHEPHERD AND

LABRADOR RETRIEVER BREEDS OF DOGS

ANANDARAJ, A.

I .D. No. MVM 10059 (VSR)

DEPARTMENT OF VETERINARY SURGERY AND RADIOLOGYMADRAS VETERINARY COLLEGE

CHENNAI - 600 007TAMIL NADU VETERINARY AND ANIMAL SCIENCES UNIVERSITY

2012

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HIP ASSESSMENT FOR DYSPLASIA DURING PRE AND POST

SKELETAL MATURITY IN GERMAN SHEPHERD AND

LABRADOR RETRIEVER BREEDS OF DOGS

ANANDARAJ, A.

I .D. No. MVM 10059 (VSR)

Thesis submitted in part fulfilment of the requirements

for the degree of

MASTER OF VETERINARY SCIENCE

in

VETERINARY SURGERY AND RADIOLOGYto the

TAMIL NADU VETERINARY AND ANIMAL SCIENCES UNIVERSITY

CHENNAI – 600 051

DEPARTMENT OF VETERINARY SURGERY AND RADIOLOGY

MADRAS VETERINARY COLLEGE

CHENNAI - 600 007

TAMIL NADU VETERINARY AND ANIMAL SCIENCES UNIVERSITY

2012

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TAMIL NADU VETERINARY AND ANIMAL SCIENCES UNIVERSITYDEPARTMENT OF VETERINARY SURGERY AND RADIOLOGY

MADRAS VETERINARY COLLEGE, CHENNAI - 600 007

CERTIFICATE

This is to certify that the thesis entitled “HIP ASSESSMENT FOR DYSPLASIA

DURING PRE AND POST SKELETAL MATURITY IN GERMAN

SHEPHERD AND LABRADOR RETRIEVER BREEDS OF DOGS” submitted

in part fulfilment of the requirements for the degree of MASTER OF

VETERINARY SCIENCE in VETERINARY SURGERY AND RADIOLOGY

to the TAMIL NADU VETERINARY AND ANIMAL SCIENCES

UNIVERSITY, CHENNAI-600051, is a record of bonafide research work carried

out by ANANDARAJ, A., under my supervision and guidance and that no part of

this thesis has been submitted for the award of any other degree, diploma, fellowship

or other similar titles or prizes and that the work has not been published in part or

full in any scientific or popular journal or magazine.

Date : (Dr. R. JAYAPRAKASH)Place: Chennai - 600007 CHAIRMAN

RECOMMENDED

Date: EXTERNAL EXAMINER

APPROVED BY

Chairman :

(Dr. R. JAYAPRAKASH)

Members :

1. (Dr. S. AYYAPPAN)

Date:

Place: Chennai – 600007 2. (Dr. A.P. NAMBI)

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CURRICULUM VITAE

Name of the student : ANANDARAJ, A.

Date of birth : 05.06.1986

Place of birth : Kallakurichi, Tamil Nadu

Major field of specialization : Veterinary Surgery and Radiology

: Completed B.V.Sc. and A.H degree in the

year 2009 from Madras Veterinary

College, Vepery, Chennai – 600 007.

Marital status : Unmarried

Permanent address : 41, K. Mamanandal Road,

Kallakurichi.

Villupuram District,

Tamil Nadu.

Pin: 606 202

Mobile: 9600725750

Mail ID: [email protected]

Membership in professional

Societies

: Member of Tamil Nadu State Veterinary

Council, Chennai.

mailto:[email protected]

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Dedicated

to My Beloved Family

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Acknowledgement

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ACKNOWLEDGEMENT

Gratitude cannot be seen or expressed, it can only be felt deep in heart and is

beyond description. Although thank is poor expression of debt of gratitude one feels,

yet there is no better way to express it.

Words fall flat when describing my sense of gratitude and thanks to the

Chairman, Dr. R. Jayaprakash, Ph.D., Professor, Department of Veterinary

Surgery and Radiology, Madras Veterinary College, Chennai- 7 for his latitude to

pursue my research, innovative suggestions, constant and continuous encouragement

throughout the period of study, the guidance when things went bad and his kindness

for understanding life.

I profoundly acknowledge and sincerely thank the Member of the Advisory

Committee Dr. S. Ayyappan, Ph.D., Professor, Department of Clinics, Madras

Veterinary College, Chennai- 7 for his continuous support, valuable comments,

critical suggestion, laudable counseling, encouragement and timely help in all

academic affairs throughout the study.

I express my sincere gratitude to the Member of Advisory Committee

Dr. A.P. Nambi, Ph.D., Professor and Head, Department of Veterinary Clinical

Medicine Ethics and Jurisprudence, Madras Veterinary College, Chennai-7 for his

practical and valuable suggestions, constant encouragement throughout the study.

I am grateful to Dr.B.Justin William, Ph.D., Professor and Head,

Department of Veterinary Surgery and Radiology for his expert advice, technical

guidance, immeasurable help and suggestions in carrying out my research work.

I express my profuse thanks to Dr.Ravi Sundar George, Ph.D., Professor,

Department of Clinics, for his keen interest, valuable suggestions and

encouragement throughout the period of my study.

I am grateful to Dr.R.Suresh Kumar,Ph.D., Professor and Head,

Department of Veterinary Surgery and Radiology for his valuable suggestions and

encouragement.

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I am extremely thankful and grateful to Dr.Capt.G.Dhanan Jaya RaoPh.D., Professor and Head, Resident Veterinary Officer and Head, MadrasVeterinary College, Dr.L.Nagarajan, Ph.D., Professor, Department of Clinics andDr.C.Ramani, Ph.D., Professor, Department of Veterinary Surgery and Radiologyfor their valuable suggestions, constant encouragement throughout the study.

It’s a pleasure to pay tribute to Dr.Shafiuzama, Ph.D., Associate Professorand Dr.A.Arun Prasad , Ph.D., Assistant Professor, Department of VeterinarySurgery and Radiology who had and have persistent confidence in me even when Ididn’t believe in myself. They were always there for me by constantly encouragingand pushing me to heights by providing hands on training and creating a pleasant,fun filled working environment. They have been showering patience and support onme from day one I entered this department. They have always encouraged me to liveintensively even when I was thinking about doing something else. They have alwaysbeen beside me during my happy and hard moments to motivate me.

I express my deep sense of gratitude to Dr.R.Ganesh, Ph.D., Professor,Department of Veterinary Surgery and Radiology and Dr. Mala Shammi, Ph.D.,Professor, Department of Clinics for their valuable suggestions, continuousencouragement and moral support given during my study.

I would like to express my special thanks to Dr.R.Sivashankar, M.V.Sc.,Assistant Professor, Department of Veterinary Surgery and Radiology, Dr.Velavan,Ph.D., Assistant Professor, Veterinary Teaching Clinical Complex, VC &RD,Orthanadu and Dr.Gokul, M.V.Sc., Assistant Professor, Department of Clinics,fortheir crucial help when I was struggling to get articles for my research.

I am extremely grateful to Dr.B.Murali Manohar, Ph.D., The Dean,Madras Veterinary College and Dr.S.Prathaban, Ph.D., Director of Clinics,TANUVAS for providing all the facilities for the study.

I am thankful to Dr.N.V.V.Hari Krishna, Ph.D., for his help and valuablesuggestions during my research.

I am thankful to Dr.V. Arun Ph.D and Dr. Anushya who in the inspirationfor my post graduate studies and funds. I would like to thank him for being the firstperson who taught me the way, to proceed with my research. His willingness toshare his bright thoughts were very fruitful for shaping up my ideas and future. I

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doubt that whether I will ever be able to convey my thanks fully, but I owe him myeternal gratitude.

I extend my heartfelt thanks to my batch-mates Dr. A. Elamaran, M.V.Sc.Research Scholar, Department of Pharmacology and Toxicology andDr. A. Anantharaj, M.V.Sc. Research Scholar, Department of Meat Science,Madras Veterinary College, for working with me in odd hours so that I could finishmy work as scheduled.

I am indebted to all my friends and colleagues Dr.Harish Kulkarni,Dr.S.Ramanathan, Dr.A.Rajalingam, Dr.V.Bhuvana, Dr.R.Reena, Dr.Nithin,Dr.Manoj, Dr.Bharathi, Dr.Anirudh, Dr.Pradnya, Dr.Naina, Dr.Sivaprakasam,Dr.S.Prabhu, Dr.A.Arun, who have lent their hands to my thesis knowingly andunknowingly through various means.

I am thankful to Mr. Jai Ganesh, Technician for helping me with X-raysand Mr. Ranganathan, Mr. Kumar and Mr. Shiva Attendors who have helped meextremely in preparation of the patient.

I place my heartful thanks to my friends Mr.Pargunan,Dr. Siranjeevikumar, Dr. N. Arvindraj, Dr. K. Deeban, Dr. Sudharshan,Dr. Sangameswaran, Dr.Enbavelan, Dr.Balaji and Dr. S. Veerapandiyan, fortheir needful help and pleasant company in my college life.

I thank to the Tamil Nadu Veterinary and Animal Sciences University foroffering the TANUVAS Merit Scholarship to my post graduate studies.

I am always grateful to my father Mr. G. Annadurai, my motherMrs. Indirani, my sister Ms.A.Sivapriya and for their unconditional love whichhas raised me to this level.

Lord! I am always thankful and feel blessed for giving me patience andstrength to overcome the difficulties which crossed my way in accomplishment ofthis endeavor.

I also express my apology if I have failed to thank anyone of them for theirhelp.

(ANANDARAJ, A.)

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Abstract

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ABSTRACT

Title : HIP ASSESSMENT FOR DYSPLASIADURING PRE AND POST SKELETALMATURITY IN GERMAN SHEPHERDAND LABRADOR RETRIEVERBREEDS OF DOGS

Name of the student : ANANDARAJ, A.

Degree for which thesissubmitted

: M.V.Sc. in Veterinary Surgery & Radiology

Name of the Chairman : Dr. R. JAYAPRAKASH, Ph.D.,Professor,Department of Veterinary Surgery andRadiology,Madras Veterinary College,Chennai- 600 007

Department : Veterinary Surgery and Radiology

Place : Madras Veterinary College,Chennai – 600 007

Year and University : 2012, Tamil Nadu Veterinary and AnimalSciences University,Chennai-600 051

Dogs presented with clinical signs of hip dysplasia to the Small Animal

Orthopaedic unit of Madras Veterinary College Teaching Hospital were selected for

the study. Clinically hip dysplastic German shepherd and Labrador retriever breeds

of dogs were grouped into two groups of six numbers and subjected to hip

assessment before and after skeletal maturity of long bones. The incidence of hip

dysplasia with regard to age, breed and sex of 322 dogs during study period were

recorded as percentage.

The clinical signs, physical palpation by Ortolani manouver and haemato-

biochemical parameters were studied and recorded in both the groups. Under general

anaesthesia radiography of hips was performed in different positioning methods

namely, Standard Ventro dorsal view(SVDV), Distraction view(DV), Weight

bearing view, Dorsal acetabular rim view and 60 degree stress view. From those hip

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positioning views, six different quantitative measurements of hips were calculated to

grade the hips for dysplasia namely Norberg angle (NA), Distraction index (DI),

Dorsolateral subluxation index (DLSI), Acetabular slope angle (ASA), Central edge

angle (CEA) and Subluxation index (SI).

Management and feeding schedule were advised during skeletal maturity

period. The quantitative radiographic assessments of hips were repeated after

skeletal maturity of long bones in all the cases in both the groups. The initial and

final scores of quantitative radiographic hip assessment before and after skeletal

maturity period were correlated and analyzed statistically.

The score obtained from the above six quantitative radiographic methods

were statistically correlated with each other and the best related methods were

identified and discussed critically.

The clinical symptoms, physical palpation by Ortolani maneuver were

correlated with those quantitative measurements and found that in group I and group

II dogs there was an improvement in pain score during skeletal maturity period

whereas Lameness score was improved only in group I dogs.

No significant difference observed in hematological and biochemical

parameters among Group I and Group II animals between pre and post skeletal

maturity period. Correlation between the Quantitative radiographic measurements

were showed that high correlation between NA and DLSI, DI and SI. More relative

correlation was seen between NA to DLSI and DI to SI. DI highly correlated with SI

in both groups. Values which were normal and near normal, highly correlated with

each others in all quantitative radiographic assessment methods.

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Contents

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CONTENTS

CHAPTERNO.

TITLEPAGE

NO.

LIST OF TABLES

LIST OF FIGURES

LIST OF PLATES

LIST OF ABBREVIATIONS

I INTRODUCTION 1

II REVIEW OF LITERATURE 3

2.1 Incidence of hip dysplasia in dogs 3

2.1.1 Congenital 3

2.1.2 Breed predisposition 3

2.1.3 Environmental factors 4

2.1.4 Nutrition 4

2.1.5 Hormonal effects 6

2.1.6 Level of Activity 7

2.2 Pathophysiology 8

2.3 Clinical signs 9

2.3.1 Pain 9

2.3.2 Lameness 9

2.3.3 Gait 9

2.4 Physical examination 10

2.4.1 Ortolani sign 10

2.4.2 Barden`s test 11

2.5 Radiological signs 11

2.6 Quantitative radiological measurements 13

2.6.1 Norberg angle 13

2.6.2 Distraction index 14

2.6.3 Subluxation index 16

2.6.4 Dorsolateral Subluxation index 16

2.6.5 Central edge angle 17

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CHAPTERNO.

TITLEPAGE

NO.

2.6.6 Acetabular slope angle 17

2.7 Medical management 18

2.7.1 Neutraceuticals 18

2.7.2 Dietary management 18

2.7.3 Physical therapy 18

2.7.4 Genetic control 19

III MATERIALS AND METHODS 203.1 Selection of cases 203.1.1 Design of experiment 203.2 Incidence of age, breed and sex 223.3 Clinical signs 223.3.1 Pain 223.3.2 Lameness 223.3.3 Physical palpation 233.3.3.1 Ortolani Sign 233.4 Haematological and Biochemical Parameters 233.4.1 Haematological Parameters 233.4.2 Biochemical parameters 233.5 Anaesthetic protocol 243.6 Quantitative radiographic assessment 243.6.1 Hip Extended view 243.6.1.1 Radiographic signs 243.6.1.2 Norberg angle 263.6.2 Distraction view and distraction index 263.6.3 Dorsoventral view for Dorsolateral subluxation score 313.6.4 Dorsal acetabular rim view 353.6.4.1 Central edge angle 353.6.4.2 Acetabular slope angle 353.6.5 Stress radiographic view 383.7 Degree of hip dysplasia in different quantitative assessment

methods38

3.8 Statistical analysis 41

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CHAPTERNO.

TITLEPAGE

NO.

IV RESULTS 42

4.1 Incidence 42

4.1.1 Age 42

4.1.2 Sex 42

4.1.3 Size of the animal 42

4.1.4 Breed 42

4.2 Clinical symptoms 46

4.2.1 Pain 46

4.2.2 Lameness 46

4.3 Physical Palpation findings 49

4.3.1 Ortolani sign 49

4.4 Haematological and biochemical parameters 49

4.4.1 Haemoglobin 49

4.4.2 Packed Cell volume 49

4.4.3 Red Blood Cell Count 51

4.4.4 White Blood Cell Count 51

4.4.5 Neutrophils 51

4.4.6 Lymphocytes 51

4.4.7 Serum alkaline phosphatase 52

4.4.8 Total protein 52

4.4.9 Albumin 52

4.4.10 Calcium 53

4.4.11 Phosphorus 53

4.5 Quantitative radiographic assessment 53



4.5.3 Dorsolateral subluxation score 57

4.5.4 Central edge angle 57

4.5.5 Acetabular slope angle 58

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CHAPTERNO.

TITLEPAGE

NO.


4.6 Correlation between quantitative radiographic assessments 59

4.6.1 Correlation between Quantitative Radiographic AssessmentTechniques in group I dogs during pre and post skeletalmaturity period

59

4.6.2 Correlation between Quantitative Radiographic AssessmentTechniques in group II dogs during pre and post skeletalmaturity period

66

V DISCUSSION 69

5.1 Incidence 69

5.1.1 Age 69

5.1.2 Sex 69

5.1.3 Size of the animal 69

5.1.4 Breed 70

5.2 Clinical symptoms 70

5.2.1 Pain 70

5.2.2 Lameness 70

5.3 Physical Palpation by Ortolani manoeuver 71

5.4 Haematological and biochemical parameters 71

5.5 Quantitative Radiographic Assessment 71



5.5.3 Dorsolateral subluxation score 73

5.5.4 Central edge angle and Acetabular slope angle 73


5.6 Correlation between different quantitative radiographicassessment techniques

74

VI SUMMARY 75

BIBLIOGRAPHY 79

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List of Tables

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LIST OF TABLES

TableNo.

TitlePageNo.

1 Incidence of Hip dysplasia based on size of the animal 44

2 Pain scoring in Group I and Group II dogs during pre and postskeletal maturity period

47

3 Lameness scoring in Group I and Group II dogs during pre andpost skeletal maturity period

48

4 Ortolani sign in Group I and Group II dogs during pre and postskeletal maturity period

50

5 Hematological and biochemical parameters in group I dogs 54

6 Hematological and biochemical parameters in group II dogs 55

7 Quantitative Radiographic measurements in group I dogsduring pre skeletal maturity period

60

8 Quantitative Radiographic measurements in group I dogsduring post skeletal maturity period

61

9 Quantitative Radiographic measurements in group II dogsduring pre skeletal maturity period

62

10 Quantitative Radiographic measurements in group II dogsduring post skeletal maturity period

63

11 Paired `t`-Test in group I dogs during Pre and Post skeletalmaturity period

64

12 Paired `t`-Test in group II dogs during Pre and Post skeletalmaturity period

65

13 Correlation between Quantitative Radiographic AssessmentTechniques in group I dogs during pre and post skeletalmaturity period

67

14 Correlation between Quantitative Radiographic AssessmentTechniques in group II dogs during pre and post skeletalmaturity period

68

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List of Figures

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LIST OF FIGURES

Figure

No.Title

Page

No.

1 Age wise incidence of hip dysplasia 43

2 Sex wise incidence of hip dysplasia 43

3 Incidence in Large sized breeds 45

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List of Plates

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LIST OF PLATES

PlateNo.

TitlePageNo.

1 Clinical signs of hip dysplasia 21

2 Positioning the dog for Norberg angle assessment -standard ventro dorsal view

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3 Radiograph showing the measurement of norbregangle from standard ventro dorsal view

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4 Custom deviced distractor used for distraction indexassessment

28

5 Positioning the dog for distraction index assessment -distraction view

29

6 Radiograph showing the measurement of distractionindex from distraction view

30

7 Positioning foam bed used for dorsolateralsubluxation index assessment

32

8 Positioning the dog for dorsolateral subluxation indexassessment - weight bearing view

33

9 Radiograph showing the measurement of dorsolateralsubluxation index from weight bearing view

34

10 Positioning the dog for central edge angle andacetabular slope angle assessment - dorsal acetabularrim view

36

11 Radiograph showing the measurement of central edgeangle and acetabular slope angle from dorsalacetabular rim view

37

12 Positioning the dog for subluxation index assessment- 60 degree stress view

39

13 Radiograph showing the measurement of subluxationindex from 60 degree stress view

40

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List of Abbreviations

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LIST OF ABBREVIATIONS

ASA - Acetabular Slope Angle

CEA - Central Edge Angle

CHD - Canine Hip Dysplasia

DI - Distraction Index

DJD - Degenerative Joint Disease

DLSI - Dorso Lateral Subluxation Index

HAP - Half Axial Positioning

HD - Hip Dysplasia

HJL - Hip Joint Laxity

NA - Norberg Angle

OA - Osteoarthritis

QHAT - Quantitative Hip Assessment Technique

SI - Subluxation Index

SVDV - Standard Ventro Dorsal View

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Introduction

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CHAPTER I

INTRODUCTION

Hip dysplasia in dogs is a multi factorial orthopaedic disease affecting the

hip joints. The disease is polygenetic in origin and hence its control is attributed to

selective breeding of dogs with normal hips. The main reasons for hip dysplasia are

poor genetic quality of breeding dogs, indiscriminate breeding and inbreeding

between dysplastic littermates (Ginja et al., 2008b). The occurrence of hip dysplasia

may get reduced only if the genetic quality of breeding animals is ascertained more

exactly (Janutta et al., 2008). This can be achieved by estimating the breeding value

of an animal through anatomical and physiological assessment of hips by

radiographic procedure.

In dogs, hip dysplasia could present substantial challenges to the veterinarian

because anatomical features of hip joint differ differently with different breeds and

the fact that hip dysplasia is often diagnosed wrongly and sometimes delayed

(Fluckiger et al., 1999). Therefore many hip assessment techniques were developed

to diagnose this genetic condition at different age groups to select dogs for potential

breeding and management.

Different techniques of radiographic assessment for diagnosis of hip

dysplasia are based on subjective and quantitative evaluations, evolved over the

years. Among these, subjective assessment depends on the cumulative assessment of

a hip joint by a team of radiologists, which in turn needs extensive monitoring and

recording system with less dependable results (Farrell et al., 2007).

A large number of quantitative measurement methods are being practiced in

different countries all over the world to diagnose hip dysplasia. No single method

has been proved to be an effective predictor of the disease (Fries and Remedios,

1995).

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Based on the above facts, this study was undertaken to carryout different

quantitative hip assessment techniques on skeletally immature and mature German

Shepherd and Labrador Retriever breeds of dogs with the following objectives.

1. To study the incidence and aetiology of hip dysplasia in German

shepherd and Labrador retriever breeds of dogs.

2. To study the clinical symptoms, physical palpation, haemato-

biochemical parameters and radiological signs in German shepherd and

Labrador retriever breeds of dogs.

3. To correlate different hip assessment techniques during pre and post

skeletal maturity period in German shepherd and Labrador retriever

breeds of dogs.

4. To evaluate various radiographic procedures used for hip assessment

during pre and post skeletal maturity period in German shepherd and

Labrador retriever breeds of dogs.

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Review of Literature

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CHAPTER II

REVIEW OF LITERATURE

2.1. INCIDENCE OF HIP DYSPLASIA IN DOGS

2.1.1. Congenital

Mackenzie et al. (1985) stated that hip dysplasia was a polygenic trait caused

by the interaction of hundreds of genes, each contributing a small part to the disease.

At least one pair of these genes was believed to be recessive. The authors found that

it was an additive trait where the severity of an individual's disease was determined

by the number of affected genes present.

Mäki et al. (2000) found that dogs with a normal radiographic phenotype

could still be carriers of certain dysplasia genes and transmit these genes to their

offspring.

Mäki et al. (2004) observed that hip dysplasia (HD) was an inherited, non-

congenital disease that was particularly prevalent in large and giant breeds of dog.

The authors reported that some of the possible major genes were found to be

recessive, making the use of phenotypic selection against HD ineffective resulting in

very small or negligible genetic progress.

Ginja et al. (2008a) stated that Hip Joint Laxity heritability was higher than

the heritability of Hip Dysplasia at 0.85 and 0.43 respectively.

2.1.2. Breed predisposition

Lust et al. (1973) reported that Labrador Retrievers had a high incidence (20

to 30 per cent) of hip dysplasia, and the period between 3 and 8 months appeared to

be important since during that time the initial diagnosis of the disease was made.

Smith et al. (1990) observed that dogs with a DI less than 0.3 did not

develop CHD. In a similar study, 87 per cent of Labrador Retrievers with a DI less

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than 0.4 at the age of 4 months developed normal hips, whereas 57 per cent of dogs

with a DI 0.4 or greater became dysplastic.

Popovitch et al. (1995) reported that, with the same DI, German shepherd

dogs tended to develop coxarthrosis more readily than Rottweilers breeds of dogs.

Culp et al. (2006) reported mean Norberg angle for German shepherd dogs

was 99.6 and ranged from 86 to109 and for Labrador retriever was 101 ranged

from 81 to110 measured from three hundered and fifty clinically normal dogs.

2.1.3. Environmental factors

Kasstrom (1975) stated that without genetic predisposition, environmental

influences alone could not create hip dysplasia in dogs.

Bennett (1987) found no evidence in the scientific literature that mega dose

of vitamin C or any other multi-vitamin/mineral supplement were beneficial in

reducing the effects or preventing hip dysplasia

Mäki et al. (2000) observed that the phenotypic expression of HD in dogs

genetically predisposed to the condition might be modified by environmental risk

factors such as nutrition, exercise, bodyweight, birth weight, number of puppies in

the litter, age of the dam, floor cover, pre-weaning mortality rate in the litter, season

of birth and hip laxity.

Silvestre et al. (2007) found that expression of HD genes would be

influenced by a number of environmental factors.

2.1.4. Nutrition

Kasstrom (1975) reported that a higher than needed caloric intake during the

rapid growth phase might result in earlier and more severe dysplastic changes when

the genetic potential for dysplasia was present. Lower caloric intake might minimize

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or delay the evidence of dysplasia in the same dog, but would not change the

genotype.

Belfield (1976) stated that, dogs could synthesis vitamins necessary for

collagen formation. Feeding high doses of vitamin C to pregnant bitches and their

offspring until 2 years of age was reported to eliminate hip dysplasia.

Bennett (1987) stated that excess vitamin C in puppies’ caused

hypercalcemia and might delay bone remodeling and cartilage maturation. There

was no scientific evidence that supplementing high doses of vitamin C in the diet of

growing puppies prevented hip dysplasia.

Hansen (1989) reported that there was no difference in plasma amino acid

concentrations between normal and dysplastic dogs.

Hazewinkel (1989) reported that high calcium decreased osteoclastic

activity, delaying endochondral ossification and skeletal remodeling. The absolute

amount of calcium rather than the calcium:phosphorus ratio was more important.

The author also studied that young dogs did not have a protective mechanism

against excess dietary calcium. High dietary levels increased the amount of calcium

absorbed from the gastrointestinal tract.

Hazewinkel (1994) stated that nutrition was a major environmental factor

influencing the development of hip dysplasia, which changed the frequency and

severity in genetically predisposed individuals, but it did not cause hip dysplasia. No

dietary deficiencies were known to influence the development of hip dysplasia, but

current research suggested that dietary excess of carbohydrate was important

contributing factors. Current recommendations for large, growing dogs are to feed

15 grams of protein, 0.7 gram of calcium, and 30 IU of vitamin D per 1000 kJ of

metabolizable energy. The author also reported that, vitamin D increased intestinal

calcium absorption and renal resorption, excess vitamin D had an effect similar to

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that of excess calcium. Excess dietary calcium and vitamin D might contribute to the

development of hip dysplasia in genetically predisposed individuals and should be

avoided in young, rapidly growing dogs.

Kealy et al. (2000) stated that developemental orthopedic diseases with a

demonstrated nutritional aetiology included canine hip dysplasia and

Osteochondritis Dissecans. The authors found that the development of degenerative

joint disease associated with CHD could be manipulated to some extent by limited

food consumption.

2.1.5. Hormonal effects

Priester and Mulvihill (1972) studied the relative risk of sex, size and breed

for canine hip dysplasia and reported that males and females were equally affected.

The risk in giant breeds was 50 times more than small or medium sized breeds.

Wallace (1987) stated that estrogen given to puppies could induce hip

dysplasia, but Riser et al. (1985) stated that estrogen levels in dysplastic pups were

not higher than in normal pups.

Corley and Keller (1989) reported that, a number of hormones, including

estrogen, relaxin, growth hormone, parathyroid hormone and insulin had been

investigated as potential causes or contributing factors in hip dysplasia.

Greg Keller (2006) stated that oestrus appeared to affect the reliability of

diagnosis in some females during which some animals demonstrated a degree of

subluxation (laxity) that was not present when the bitch was out of season, possibly

due to the relaxation effects of estrogens on the ligaments and joint capsule.

Radiography of these bitches might result in a false diagnosis of HD. The author

suggested that following pregnancy, radiographs be taken at least one month after

weaning the off spring.

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2.1.6. Level of Activity

Barr et al. (1987) observed that progression of the disease varied in hip

dysplastic dogs and the clinical signs could sometimes be due to concurrent

neurological or orthopaedic diseases of the hind limbs.

Bennett and May (1995) reported that failure of muscles and skeleton to

mature together at the right time results in joint instability.

Smith et al. (1995) stated that hip joint laxity (HJL) was considered a major

risk factor leading to abnormal weight-bearing forces and subsequent development

of osteoarthritis during or after maturity.

Cardinet et al. (1997) observed that greater pelvic muscle mass was

associated with a reduced incidence of hip dysplasia.

Moore et al. (2001) described HD as a biomechanical disease characterised

by abnormal development of the hip joint and could be a highly debilitating

condition for both working and pet dogs.

Greg Keller (2006) stated that periods of prolonged inactivity might affect

the reliability of diagnosis of HD. The author observed that few animals exhibited

subluxation after prolonged periods of inactivity due to illness, weather conditions,

etc. and on later examination, when the animal was in good muscular tone, the hips

appeared normal. Therefore radiography was recommended when the animal was in

good health and muscular tone.

Manley et al. (2007) found that there were two ages at which dogs were

presented with clinical signs of hip dysplasia; younger than one year of age with hip

instability and overloading of some articular areas where in the pain was caused

mainly by tearing or stretching of the round ligament, synovitis and acetabular

microfractures and in adult dogs with chronic pain due to osteoarthritis.

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2.2. PATHOPHYSIOLOGY

Lust and Summers (1981) and Shepherd (1986) reported that pups

genetically predisposed to hip dysplasia were normal at birth. Stretching of the joint

capsule and ligament of the femoral head was observed as early as 2 weeks of age.

Mild proliferative, nonsuppurative synovitis, edema, and fibroplasia of the ligament

of the femoral head, as well as joint effusion, were present at 4th week. By 12th

week, affected individuals had changes in both the synovium and the articular

cartilage grossly with flaking and fissuring of the surface cartilage and

microscopically, surface chondrocytes were lost and changes in the matrix's

proteoglycan content and collagen fibril network had occurred.

Lust et al. (1985) reported that cartilage degeneration, joint capsule

thickening, stretching or rupture of the ligament of the femoral head, proliferation of

the dorsal acetabular rim, thickening of the femoral neck and atrophy of local

muscle was characterized in advanced hip dysplasia. At this point, joint stability

might improve or progress to complete luxation. The rate and degree of disease

progression varied with the individual and the amount of joint instability present.

Alexander (1992) reported that hip dysplasia was a biomechanical disease

where hip instability in the young dog altered the concentration of forces on the

growing femoral head and acetabulum. This affected the bone growth and

remodeling, resulting in abnormal joint conformation and secondary degenerative

joint disease. Abnormal weight bearing forces caused microfractures in the

subchondral bone of the dorsal acetabular rim and femoral head. With healing, the

bone became harder and less able to absorb shock. More force was transmitted to the

overlying cartilage, increasing its degeneration at these sites. Cartilage on the medial

aspect of the femoral head and dorsal acetabular rim was gradually worn away,

exposing the subchondral bone. The subchondral bone became sclerotic and

eburnated. Sharpey's fibers were torn, causing osteophytes to form along the joint

capsule's attachment to the acetabulum and femoral neck.

9

Kealy et al. (1993) observed that dysplastic dogs had higher synovial fluid

osmolalities than did normal dogs due to differences in synovial fluid electrolyte

concentrations of sodium, potassium and chloride.

Smith (1998) stated that synovial fluid volume had been implicated in the

pathogenesis of hip dysplasia through its effect on joint laxity. When normal

synovial fluid volumes were present, displacement of the femur created negative

intra articular pressure that tended to pull the femoral head back into the acetabulum.

This mechanism was lost when joint effusion was present.

2.3. CLINICAL SIGNS

2.3.1. Pain

Barr et al. (1987) observed that majority of dogs afflicted with HD showed

minimal or no clinical sign.

2.3.2. Lameness

Newton (1985) stated that the normal ranges of motion during different

position were: flexion 70 to 80 , extension 80 to 90 , abduction 70 to 80 ,

adduction 30 to 40 , internal rotation 50 to 60 and external rotation 80 to 90 .

Fry and Clark (1992) stated that a complete clinical examination should

include observation of the patient at rest, walking and trotting and re-examination

after vigorous exercise.

2.3.3. Gait

Ginja et al. (2008b) reported that, gait abnormalities, such as stiffness,

reduced height of step, shortened stride length, bunny hopping, difficulty in rising,

climbing stairs or in jumping over obstacles were the typical clinical signs observed

in dogs with hip dysplasia.

10

2.4. PHYSICAL EXAMINATION

Fry and Clark (1992) had categorized number of clinical tests into two

groups that could give information about the hip joint. The first group of signs

provided information on HJL, recommended mainly for use on young animals

(Ortolani, Bardens and Barlow tests) and second group of signs to detect signs of

osteoarthritis (palpation and range of motion tests).

Farrell et al. (2007) reported that in case of OA crepitus might be detected

during palpation of hip joint and the range of motion might be decreased due to the

presence of osteophytes, capsular fibrosis, subluxation or fixed luxation.

2.4.1. Ortolani sign

According to Chalman and Butler (1985) and Ginja et al. (2008c) Ortolani

test is a common physical manipulation examination used in veterinary clinical

medicine to diagnose Hip Joint Laxity. The dog is to be placed in lateral

recumbency, the examiner stands behind the animal and grasps the upper stifle

firmly putting the hip in a neutral position and the femur parallel to the surface of

the examination table. A proximally directed force is applied to the shaft of the

femur to elicit hip subluxation, while the pelvis is supported with the other hand.

Then the stifle is slowly abducted to reduce the hip joint. Hip joints are considered

to exhibit a positive Ortolani sign when a palpable or audible ‘clunk’ was present

during hip joint reduction. If a ‘clunk’ cannot be elicited, the result of the Ortolani

test was considered negative.

Puerto et al. (1999) stated that a positive Ortolani test suggested excessive

laxity, but its absence did not always indicate a tight hip. Fibrosis and thickening of

the joint capsule, and the acetabular rim and femoral head destruction prevented the

detectable “clunk”. The authors also found a significant relationship between the

result of Ortolani maneuver and radiographic distraction index in the absence of any

existing degenerative joint disease.

11

Adams et al. (2000) and Ginja et al. (2009) observed that Ortolani test also

lacked sensitivity in puppies around 8 weeks of age but was most sensitive in young

dogs older than 4 months of age.

Vezzoni et al. (2008) reported that in positive cases of HD Ortolani

technique could be used to determine the angles of reduction (AR) and angles of

subluxation (AS), as the inclination of the femur relative to the sagittal plane at the

moment of reduction and subluxation, respectively. This was particularly relevant

when a triple pelvic osteotomy or pubic symphysiodesis were being considered.

2.4.2. Barden`s test

Bardens and Hardwick (1968) stated that Barden’s test was recommended to

evaluate HJL in puppies at 6 to 8 weeks of age. With the animal on lateral

recumbency, the examiners stand behind the puppy and grasp the upper femur.

Upward pressure is applied by that hand to elevate the femur horizontally. The index

finger of the other hand is placed on the greater trochanter and its mobility is used to

estimate HJL.

Adams et al. (2000) stated that only Bardens maneuver was significantly

predictive of degenerative joint disease incidence when performed on 7.3 weeks old

puppies.

2.5. RADIOLOGICAL SIGNS

Riser (1975) reported that, the first signs of HD could be noticed as early as

30 to 60 days of age radiographically, characterised by femoral head subluxation

and delayed ossification of the craniodorsal acetabular rim in severely affected

individuals.

Morgan (1987) observed that occurrence of caudolateral curvilinear

osteophyte on the proximal aspect of femoral neck was an important radiological

12

sign of degenerative joint disease due to canine hip dysplasia in young large breed

dogs.

Corley (1992) reported radiographic changes as early as the 7th week after

birth in severely dysplastic hips, however in mild dysplasia the secondary

radiographic changes might not be apparent until 14 months of age or older.

Flückiger (1995) and Gibbs (1997) reported that a definitive diagnosis could

be made, only if characteristic signs of HD were evident on a standard ventro dorsal

radiograph of the pelvis.

Powers et al. (2004) stated that an indistinct linear sclerosis on the femoral

neck termed as puppy line had been reported as an incidental, transient radiographic

finding that could be confused with caudolateral curvilinear osteophyte in dogs up to

18 months of age but distinction between the caudolateral curvilinear osteophyte and

the puppy line had not been established. The caudolateral curvilinear osteophyte was

a distinct white line on the femoral neck while the puppy line was a less distinct line

on the femoral neck, both were seen on the extended hip ventro-dorsal pelvic

radiograph.

Szabo et al. (2007) observed that a circumferential femoral head osteophyte

was also associated with degenerative joint disease due to canine hip dysplasia. This

radiographic finding was defined as a thick, indistinctly margined to thin, faint,

radiopaque line encircling the junction of the femoral neck and head at the region of

attachment of the joint capsule.

Ginja et al. (2009) stated that radiographic studies could be separated into

two main groups: (1) to evaluate joint congruence and to detect signs of

osteoarthritis using the standard ventrodorsal hip extended view (SVDV) and (2) to

provide information on HJL demonstrated by stress radiography (PennHIP,

dorsolateral subluxation [DLS], Fluckiger and Half-Axial Position [HAP]

methods).The authors also insisted that these radiographic techniques were to be

performed under anaesthesia or heavy sedation, to facilitate accurate positioning and

decrease the need for repeat films and human restraint.

13

Risler et al. (2009) stated that the age of 24 weeks, at which time the

presence of a femoral neck line, termed caudolateral curvilinear osteophyte or

Morgan line might be predictive of subsequent canine hip dysplasia and

degenerative joint disease. If both caudolateral curvilinear osteophyte and a

circumferential femoral head osteophyte were present at 24 to 27 weeks of age and

radiographic signs of hip degenerative joint disease by one year of age were certain

in large breeds of dogs.

2.6. QUANTITATIVE RADIOLOGICAL MEASUREMENTS

2.6.1. Norberg angle

Olsson (1961) reported that Norberg angle (NA) was a measurement used in

the evaluation of canine femoral head displacement from the aetabulum. The author

stated that, for the depth to be considered normal, the cranial edge of the acetabulum

had to be considerd normal. The cranial edge of the acetabulum had to be situated

not less than 15° laterally to a line at right angles to the line between the centers of

the femoral heads. Essentially, it was established that NA of <105 was indicative of

abnormal hip status and it had to be measured on a hip extended radiographic

projection.

Smith et al. (1990) and Vezzoni et al. (2005) observed that the SVDV had

been considered to lack sensitivity while detecting HJL because the standard

position tightened the joint capsule, the ligaments of the femoral head and associated

muscles.

Corley (1992) recommended the Orthopaedic Foundation for Animals (OFA)

guidelines commonly used in the United States for scoring of hip dysplasia. In that

seven grades were used (three normal, one borderline and three dysplastic).

Flückiger (1995) stated that there were other screening and scoring methods

in other countries, such as the system used in Switzerland, which evaluated six

parameters using a score of 0 to 5 (total score ranging from 0 to 30).

14

Gibbs (1997) stated that the British Veterinary Association/Kennel Club

scoring scheme was commonly used in UK and was based on a detailed points

system for the assessment of radiographic features. Nine parameters for each joint

were evaluated and each parameter was given a score between 0 and 6 (except for

one parameter which was scored 0 to 5). The total score thus ranged from 0 to 106.

Ginja et al. (2008b) stated that the SVDV was a universal view that involves

placing the dog in dorsal recumbency on the X-ray table, with the rear limbs

extended parallel to each other and the stifles internally rotated. The correct

positioning of the dog was of utmost importance for an accurate radiographic

interpretation, the pelvis should be positioned symmetrically with the femurs

parallel to each other and the patella superimposed over the centre of the femoral

condyles.

Genevois et al. (2008) stated that, Federation Cynologique Internationale

followed in France, which does not require any sedation or anaesthesia for

radiographic evaluation of hips. Lack of muscle relaxation clearly influenced the HD

score and was preferred by owners.

2.6.2. Distraction index

Smith et al. (1990) stated that the PennHIP method required appropriate

training to certify users and incorporated three radiographic views of the dog in the

supine position: hip-extended, compression and distraction. The distraction view

was taken with the hips at a neutral position and maximally displaced laterally using

the PennHIP distractor and was used to estimate HJL by calculating the distraction

index (DI). To calculate the DI, the distance between the geometric centres of the

acetabulum and the femoral head was divided by the radius of the femoral head. The

DI ranged from 0 to 1, with 0 representing full congruency of the hip joint and 1

representing complete luxation.

Heyman et al. (1993) positioned the hindlimbs at an 80° angle to the table

top, avoiding joint capsule tensioning. The authors used a distractor but could

15

achieve lateral displacement only because there was no dorsal force component. The

degree of instability was quantified by a dimensionless distraction index (DI = d/r),

defined as the ratio of the distance from the center of the femoral head to the center

of the acetabulum (d) and the radius of femoral head (r).

Lust et al. (1993), Ginja et al. (2008c) and Ginja et al. (2009) found that HJL

estimated using the distraction index in stress radiographs in dogs at 2 months and 4

months of age was correlated or associated with HJL and HD after 1 year of age.

Popovitch et al. (1995) reported that Penn HIP(University of Pennsylvania

Hip Improvement Program, Philadelphia, PA) method was another radiographic

method to assess hip status. It incorporated 3 radiographic views: standard hip-

extended projection, a compression projection and a distraction projection. The

distraction radiograph was originally developed to quatitate the amount of passive

hip laxity of the coxofemoral joint reported as a distraction index (DI). Hip laxity

(DI) profiles vary among breeds, but in general, a DI of < 0.3 for all breeds signified

minimal chance of developing radiographic DJD. Dogs with DI values 0.3 had an

increased susceptibility for radiographic hip DJD as the DI increases.

According to Smith et al. (1995) the admissible DI range for normal

coxofemoral development varied among breeds.

Adams et al. (2000) stated that distraction indices measured from

radiographs in 6.5 to 9.0 weeks old pups might not correlate with PennHip

measurements in the same dogs at one year of age. The authors also studied hips

with distraction index measurement greater than 0.60 or greater than 0.70 at 7.3

weeks, 24 per cent and 33 per cent developed degenerative joint disease by one year

respectively.

Culp et al. (2006) reported that the linear correlation between NA and DI

was (0.336) in German shepherd breed of dogs and (0.452) in Labrador retriever

breed of dogs and also reported that the concordance of positive susceptibility using

16

NA threshold of <105 and DI threshold of >0.32 was 56 per cent and 44 per cent in

German shepherd and Labrador retriever breeds of dogs respectively.

2.6.3. Subluxation index

Smith et al. (1990) stated that, coxofemoral laxity was considered the most

important factor promoting CHD. The degree of coxofemoral joint laxity could be

evaluated reliably using the standard radiographic positioning of the dog with the

hindlimbs pulled caudally and rotated inwards because SVDV method caused

overextension of the hip joint and spiral tensioning of the nonelastic joint capsule

that resulted in repositioning of a subluxated femoral head back into the acetabulum.

Flückiger et al. (1999) stated that the Flückiger method to created the stress

view of hip joint in the dogs placed in dorsal recumbency on the X-ray table. The

femurs were positioned at a 60° angle to the table surface, the stifles were adducted

and manually pushed craniodorsally by the examiner during X-ray exposure. The

degree of laxity was calculated in the same way as the DI but was defined as the

subluxation index.

2.6.4. Dorsolateral Subluxation index

Farese et al. (1998) reported that for DLS test, no manual restraint was

required, the dogs were placed in sternal recumbency in a ‘kneeling’ position on a

foam containing openings for the hind limbs. The hind limbs were fixed in an

adducted position with medical tape, proximal to the stifles and around the hocks.

The HJL was estimated by calculating the DLS score. To calculate the DLS score,

the perpendicular distance between the most medial edge of the femoral head and

the lateral margin of the cranial acetabulum was divided by the diameter of the

femoral head. The DLS showed a strong correlation with the DI in 8 month old

dogs.

Farese et al. (1999) found that DLS and DI measured different components

of the hip joint; DLS test was specially indicated to evaluate the chondro-osseous

conformation whereas DI represented passive laxity of the joint and was

17

independent of the potential stabilising effects of the acetabulum on femoral head

positioned within the joint. The authors noticed that intra- articular injection of 2 mL

of sodium hyaluronate increased the mean DI by 56 per cent and decreased the mean

DLS score minimally 2.5 per cent.

2.6.5. Central edge angle

Meomartino et al. (2002) calculated the mean central edge angle for normal

and dysplastic dogs, as

No signs of dysplasia - 16.91

Borderline hips joints - 12.55

Mild dysplasia - 10.65

Moderate dysplasia - 6.62

Severe dysplasia - 9.25

2.6.6. Acetabular slope angle

Slocum and Devine (1990) measured the acetabular slope angle from dorsal

acetabular rim radiographic view for evaluation of acetabualr coverage.

Meomartino et al. (2002) calculated the mean acetabular slope angle for

normal and dysplastic dogs, as

No signs of dysplasia - 7.14

Borderline hips joints - 11.6

Mild dysplasia - 11.84

Moderate dysplasia - 15.04

Severe dysplasia - 25.23

18

2.7. MEDICAL MANAGEMENT

2.7.1. Neutraceuticals

Lust et al. (1992) stated that puppies treated prophylactically with

intramuscular injections of poly-sulfated glycosaminoglycans showed less

subluxation than untreated animals.

The published outcomes of long-term results of non-surgical management of

HD in dogs are controversial, some being considered favourable (Barr et al., 1987)

and others unfavourable (Farrell et al., 2007 and Vezzoni et al., 2008).

According to Manley et al. (2007) and Vezzoni et al. (2008) conservative

management may be effective in palliating the discomfort associated with HD or

HJL, but was unlikely to prevent development and progression of osteoarthritis.

2.7.2. Dietary management

Kealy et al. (1992) studied that limiting food consumption to 75 per cent of

the amount given to ad libitum-fed control dogs after 8 weeks of age resulted in a 67

per cent reduction in HD prevalence at 2 years of age.

Vezzoni et al. (2008) reported that prevention of obesity was recommended

as a way to decrease the stress placed on joints and periarticular tissues. A non-

weight bearing activity such as swimming yielded positive benefits of exercise on

muscle strength and cartilage nutrition without undesirable secondary effects.

2.7.3. Physical therapy

Riser (1975) stated that restricting exercise by confining puppies in a cage

had been reported as an alternative for young dogs with a predisposition to HD

development. By confining a puppy in a small area they stay seated for long periods,

thereby maintaining an abduction-flexion position, which supports a forced hip

congruence. However, this treatment was not recommended since such dogs did not

develop socially.

19

Barr et al. (1987) observed that some chronic hip alterations (i.e. bony

remodelling, fibrosis and thickening of the joint capsule) actually improved joint

congruity and stability, which resulted in spontaneous improvement in hind-limb

function.

Johnson et al. (1998) and Farrell et al. (2007) reported that HD was

generally diagnosed by worsening of symptoms when osteoarthritis was already at

an advanced stage that renders conservative or surgical therapy practically useless to

limit the development of the disease or its severity. Treatments were focused on

alleviating pain and improving the function of the hip joints and quality of life.

2.7.4. Genetic control

Smith (1998) stated that controlling polygenic diseases like HD required

selective breeding programmes. Since there were no definitive molecular diagnostic

tests, the animal’s genotype was estimated by evaluating hip phenotype. The

relationship between phenotype and genotype resulted in the concept of heritability,

defined as the ratio of additive genetic variance to the overall phenotypic variance.

Chase et al. (2004) and Todhunter et al. (2005) attempted the isolation of

genetic markers for diagnosis of HD in dogs and they also found that complex

segregation and molecular genetic analysis revealed that major dominant and

recessives genes for HD existed in dogs, few major genes were responsible for the

major differences in favourable or unfavourable hip conformation.

Janutta and Distl (2006) reported that the possible existence of major genes

and the detection of quantitative trait loci associated with HD could be important for

diagnosis and selection against HD, which enabled the elimination of carriers from

breeding programmes.

Farrell et al. (2007), Ginja et al. (2008b) and Janutta et al. (2008) stated that

active genetic control based on diagnostic tests for HD and selective breeding were

the best tools to achieve genetic changes decreasing the disease to acceptable levels.

20

Materials and Methods

20

CHAPTER III

MATERIALS AND METHODS

3.1 SELCTION OF CASES


Orthopedic unit of Madras Veterinary College Teaching Hospital were selected for

the study (Plate 1).

3.1.1 Design of Experiment

Based on the age of occurrence of clinical symptoms suggestive of hip

dysplasia, 12 dogs were selected for the study and grouped.

Clinically hip dysplastic German shepherd and Labrador retriever breeds of

dogs were grouped into two groups of six numbers in each groups and subjected to

hip assessment before and after skeletal maturity of long bones.

Groups Breed No of Animals Hip Assessment Period

Group I Germanshepherd

6 Before skeletalmaturity

After skeletalmaturity

Group II Labradorretriever

6 Before skeletalmaturity

After skeletalmaturity

Initial assessment : Before skeletal maturity: Assessment wasperformed between four and nine months of age.

Reassessment : After skeletal maturity: After nine months of agewith a minimum interval of three months betweenthe assessment.

21

PLATE 1

CLINICAL SIGNS OF HIP DYSPLASIA

22

3.2 INCIDENCE OF AGE, BREED AND SEX

The incidence of hip dysplasia with regard to age, breed and sex of dogs

were recorded in percentage.

3.3 CLINIAL SIGNS

The following clinical signs of hip dysplasia were studied.

3.3.1 Pain

The degree of pain in hip dysplasia was assessed by a numerical rating

system which was advocated by Hielm-Bjorkman et al. (2003). The factors

considered for pain assessment were `mood’ with a score very alert = 0, alert = 1,

neither nor indifferent = 2, indifferent = 3 and very indifferent = 4; willingness to

play games scored as very willing = 0, willing = 1, reluctant = 2, very reluctant = 3

and does not participate at all = 4; vocalization scored as never = 0, hardly ever = 1,

sometimes = 2, often =3 and very often =4; Walking, trotting, jumping and

galloping were scored as very willingly = 0, willingly = 1, reluctantly = 2, very

reluctantly = 3 and does not participate in action at all = 4; Lying down and getting

up was scored as with great ease = 0, easily = 1, neither easily nor with difficulty = 3

and with great difficulty = 4; Problems with moving after long rest and exercise

were scored as never = 0, hardly ever = 1, sometimes = 2, often = 3, very often = 4.

3.3.2 Lameness

The degree of lameness was assessed by a score system suggested by

Welsh et al. (1993). The score assigned were clinically sound = 0, barely detectable

lameness = 1, obvious lameness =2, severe head nod and resting the affected hind

leg = 3, carrying the leg at the trot = 4. The individual lameness score of left and

right hind legs in dogs of group I and group II was recorded.

23

3.3.3 Physical palpation

The physical palpation of the hip joints was performed in the dorsal

recumbency using Ortolani method of palpation under general anesthesia prior to

quantitative radiographic assessment (Chalman and Butler, 1985).

3.3.3.1 Ortolani Sign

The dog was positioned in dorsal recumbency and the examiner stood behind

the animal and grasped the stifles firmly (with the femur perpendicular to the surface

of the examination table). Pressure was applied down the shaft of the femur towards

the acetabulum. Each femur was individually abducted to its limit. In dysplastic

dogs downwards pressure on the femur elicited audible or palpable “clunk” as the

subluxated femur was reduced (Chalman and Butler, 1985).

A palpable or audible “clunk” during the technique was known as a positive

Ortolani sign. The presence or absence of Ortolani sign was recorded in percentage

in group I and group II dogs.

3.4 HAEMATOLOGICAL AND BIOCHEMICAL PARAMETERS

3.4.1 Haematological Parameters

EDTA sample of blood was collected and the haematological parameters

such as haemoglobin, PCV, red blood cell count and differential count were

recorded in both group I and II (Coles, 1986).

3.4.2. Biochemical parameters

The serum samples were collected and the biochemical parameters such as

calcium, phosphorus, serum alkaline phosphatase and total protein were estimated in

group I and II.

24

3.5. ANAESTHETIC PROTOCOL

The dogs were premedicated with atropine sulphate at the dose rate of

0.04mg/kg intramuscularly and sedated with xylazine at the dose rate of 1mg/kg

intramuscularly and general anaesthesia was induced with ketamine (at the dose rate

of 5mg/kg) and diazepam (at the dose rate of 0.125mg/kg) combination (4 ml of

Ketamine 50mg/ml + 1 ml of diazepam 5mg/ml) to effect and maintained by half the

dose of induction, as and when required.

3.6 QUANTITATIVE RADIOGRAPHIC ASSESSMENT

All the twelve dogs were anaesthetized and subjected to the following six

different quantitative radiographic hip assessment methods before skeletal maturity

of long bones.

3.6.1 Hip Extended view

The anaesthetized dog was positioned in dorsal recumbency and the cranial

position of the patient was supported with the aid of sand bags (Plate 2). The hind

limbs were held at the level of the hocks and pulled in a distal caudal direction. The

hind limbs were rotated medially to superimpose the patella over the sagittal plane

of femurs and the femurs were kept parallel to each other and along with the long

axis of the veretebrae. The paws were placed 4 to 5 inches (10 to 12.5cm) above the

table top in giant breeds of dogs and 2 to 3 inches (5 to 7.5 cm) in small breeds in

order to relive excessive tension of pelvic muscles (Rendano and Ryan, 1985).

3.6.1.1 Radiographic signs

The radiographic signs suggestive of hip dysplasia in dogs were studied from

the standard hip extended view. The radiographic signs such as subluxation of

femoral head and presence or absence of remodeling changes were observed and

recorded.

25

PLATE 2

POSITIONING THE DOG FOR NORBERG ANGLEASSESSMENT - STANDARD VENTRO DORSAL VIEW

26

3.6.1.2 Norberg angle

The standard hip extended radiographic view was used for measurement of

Norberg angle. The femoral head centers were found and joined by a straight line.

Each femoral head center was then connected to the tangential line of the ipsilateral

cranial dorsal acetabular edges. The angle subtended by the tangential line of the

dorsal acetabular edge and the line joining the femoral head centers was the Norberg

angle (Adams et al., 2000) (Plate 3).

3.6.2 Distraction view and distraction index:

For radiography of the hips in the distraction view, the dog was positioned in

dorsal recumbency. A fabricated adjustable wooden frame aluminium distractor

(Plate 4) was placed between the hind-legs, and an assistant firmly pressed it down

onto the pelvis. While grasping the hocks, the examiner pushed the knees together,

using the device as a fulcrum to impose a lateral distractive force on the hip joints.

The spacing of the distractor bars was set at approximately with the interacetabular

distance. This spacing allowed for the proper stance-phase distance between the

knees during force application of the distraction procedure. Even and firm

downward force on the distractor helped to maintain pelvic positioning while

manipulation was performed. Distraction was maintained for a short duration

sufficient enough to permit exposure of the radiographic film (Plate 5).

The DI was calculated from the following formula

DI =d/r, (Plate 6)

d- separation distance after the distraction between the femoral head center

and acetabular centre of each hip joint, measured in centimeter.

27

PLATE 3

RADIOGRAPH SHOWING THE MEASUREMENT OFNORBREG ANGLE FROM STANDARD VENTRO DORSAL

VIEW

28

PLATE 4

CUSTOM DEVICED DISTRACTOR USED FOR DISTRACTIONINDEX ASSESSMENT

29

PLATE 5

POSITIONING THE DOG FOR DISTRACTION INDEXASSESSMENT - DISTRACTION VIEW

30

PLATE 6

RADIOGRAPH SHOWING THE MEASUREMENT OFDISTRACTION INDEX FROM DISTRACTION VIEW

31

r – radius of the femoral head of that particular hip joint measured in

centimeters.(Smith et al., 1990)

3.6.3 Dorsoventral view for Dorsolateral subluxation score:

The hind limbs of the anaesthetized dogs were positioned in an adducted

position with medial tape, proximal to the stifle for the DLS test. The hocks were

adducted and held together with tape. The dog were positioned in sternal

recumbency an a kneeling position on a foam pad, with their hock joints extended,

the stifles flexed and placed through a cut opening of 7`` diameter in the foam pad

measuring 45”×24” ×4” (Plate 7). Cotton was packed within the cut opening

between the foam pad and the thighs of the dog to help in proper positioning of the

hind limb. The hole in the pad allowed the stifle to have direct contact with the table

and transmit force along the longitudinal axis of the femur to the hip joints,

permitting dorsolateral subluxation of the femoral heads. The hips were slightly

extended so that the diaphyses were nearly perpendicular to the table but not

superimposed over the femoral heads and acetabulae. The hocks, hind paws and

trochanter were checked for symmetry from the lateral and caudal aspects. The

image was evaluated for positioning and symmetry on the doesoventral radiographic

projection (Plate 8).

The DLS was a percentage calculated from the dorsoventral projection view

in a DLS test. It was calculated from the formula

DLS score = d/Ø×100 (Plate 9)

d is the distance between the perpendicular lines dropped from the dorsal

cranial acetabular edge and the perpendicular lines from the line joining the dorsal

acetabular edges tangential to the femoral head of eah side of the coxofemoral joint

and Ø is the diameter of the femoral head of each side of the coxofemoral joint

(Farese et al., 1998).

32

PLATE 7

POSITIONING FOAM BED USED FOR DORSOLATERALSUBLUXATION INDEX ASSESSMENT

33

PLATE 8

POSITIONING THE DOG FOR DORSOLATERALSUBLUXATION INDEX ASSESSMENT - WEIGHT BEARING

VIEW

34

PLATE 9

RADIOGRAPH SHOWING THE MEASUREMENT OFDORSOLATERAL SUBLUXATION INDEX FROM WEIGHT

BEARING VIEW

35

3.6.4 Dorsal acetabular rim view

Under general anesthesia, the dog was positioned in sternal reumbency. The

hind limbs were pulled forward, so that the femurs were parallel with the long axis

of the body. A belt was placed around the dog thighs and torso. This was to pull the

femurs close to the dog`s body. The stifles were flexed so that the tibia was 90° to

the femur and the hip was internally rotated 45 so that on the radiograph the greater

trochanters did not usually interface with the dorsal acetabular rim. The hocks were

raised by placing 2 inch tape underneath the tubercalcis. This placed a pull on the

hamstring muscle and drew the tuber ischii cranially with respect to the tuber

sacrale. This caused the pelvis to be aligned vertically so the x-ray beam passed

through the shaft of the ilium (Plate 10).

The ideal position of the pelvis was vertical alignment of tuber ischii and

tuber sacrale with both the ischiatic tuberosities on the radiographic table. This

position helped to prevent any rotation in the positioning of the dog on its sternum

(Slocum and Devine, 1990).

3.6.4.1 Central edge angle

The Central edge angle was calculated from the dorsal accetabular rim view.

Central edge angle was defined by two straight lines originating from the centre of

the femoral head of each hip joint (Plate 11).

a. Tangential to the acetabular rim and

b. Parallel to the mid sagittal line respectively (Meomartino et al., 2002).

3.6.4.2 Acetabular slope angle

Acetabular slope angle was formed by a straight line tangential to the

acetabulum at the point of lateral contact with the femoral head and by a line normal

to the mid sagittal line (Meomartino et al., 2002) (Plate 11).

36

PLATE 10

POSITIONING THE DOG FOR CENTRAL EDGE ANGLE ANDACETABULAR SLOPE ANGLE ASSESSMENT - DORSAL

ACETABULAR RIM VIEW

37

PLATE 11

RADIOGRAPH SHOWING THE MEASUREMENT OFCENTRAL EDGE ANGLE AND ACETABULAR SLOPE ANGLE

FROM DORSAL ACETABULAR RIM VIEW

38

3.6.5 Stress radiographic view

This stress view was taken with the dog placed in dorsal recumbency.

Femurs were positioned at 60° angle to the table top, stifles were adducted and

manually pushed craniodorsally by a tester during exposure, the tibia served as a

lever. Such manipulation resulted in cranial, dorsal, and lateral displacement of the

femoral head in an unstable hip joint (Plate 12). Maximal subluxation was assumed

as long as the radiographic angle formed by the line connecting the two femoral

heads and the femoral longitudinal axis did not exceed 90° on each side. A slight

pelvic tilt over the long axis, reflected by a difference of the obturator foramina

diameters of up to 5 mm at their broadest, was tolerated. As more muscle tissue had

to be penetrated, exposure was increased by 30% compared with the standard

technique. The degree of laxity was quantified identical to the DI method described

by Smith et al. (1995) but was termed subluxation index (SI) instead (Plate 13), to

separate the results of the two dislocation techniques from each other. (Fluckiger,

1995 and Fluckiger et al., 1999)

3.7 DEGREE OF HIP DYSPLASIA IN DIFFERENT QUANTITATIVE

ASSESSMENT METHODS

Degree of

hip

dysplasia

NA

(Degree)

DI

(Ratio)

DLS

(Percentage)

CEA

(Degree)

ASA

(Degree)

SI

(Ratio)

Normal >105 <0.3 >60 >16 <7 <0.3

Moderate 90-105 0.3-0.7 40-60 6-16 7-25 0.3-0.5

Severe <90 >0.7 <40 <6 >25 >0.5

39

PLATE 12

POSITIONING THE DOG FOR SUBLUXATION INDEXASSESSMENT - 60 DEGREE STRESS VIEW

40

PLATE 13

RADIOGRAPH SHOWING THE MEASUREMENT OFSUBLUXATION INDEX FROM 60 DEGREE STRESS VIEW

41

Management and feeding schedule were advised during skeletal maturity

period. The quantitative radiographic assessments of hip were repeated after skeletal

maturity of long bones in all twelve cases from group I and group II. The initial and

final scores of hip assessment before and after skeletal maturity period were

correlated and analyzed statistically.

3.8 Statistical analysis


were recorded. The data obtained were analyzed statistically and discussed critically.


were statistically correlated with each other and the best related methods were

identified and discussed critically.

42

Results

42

CHAPTER IV

RESULTS

4.1. INCIDENCE

4.1.1 Age

Of the 322 dogs examined during the study period 46.27 per cent (149 dogs)

were in the age group of less than 1 year, 31.67 per cent (102 dogs) were in the age

group between 1-6 years and 22.04 per cent (71 dogs) were in the age group more

than 6 years. (Figure 1)

4.1.2 Sex

Of the 322 dogs studied 57.45 per cent (185 dogs) were males and 42.54 per

cent (137 dogs) were females. (Figure 2)

4.1.3 Size of the animal

Of the 322 dogs studied, small sized dogs weighing 1-10 kgs had an

incidence of 13.04 per cent (42 dogs), medium sized dogs weighing 11-25 kgs had

an incidence of 8.69 per cent (28 dogs) and large breeds weighing 26 kgs and above

had a high incidence of 78.26 per cent (252 dogs). (Table 1)

4.1.4 Breed

Among the 322 dogs observed, Labrador Retrievers had a high incidence of

hip dysplasia in 44.09 per cent (142 dogs), German shepherd dogs 16.14 per cent

(52 dogs), Doberman 3.72 per cent (12 dogs), Golden Retrievers 2.48 per cent (8

dogs), Rottweiler 3.10 per cent (10 dogs), Great Dane 5.59 per cent (18 dogs),

Mastiff 0.62 per cent (2 dogs) and Saint Bernard 2.48 per cent (8 dogs). (Figure 3)

43

Figure 1: Age wise incidence of hip dysplasia

Figure 2: Sex wise incidence of hip dysplasia

149

102

71

< 1 yr

1-6 yr

>6 yr

0 50 100 150 200

Male

Female

185

137

44

Table 1

Incidence of Hip dysplasia based on size of the animal

Size of animal Name of the breed No of animals

Small sized (1-10kgs)

Spitz 24

Lashapso 3

Pug 6

Terrier 3

Daschund 6

Medium sized (11-25 kgs)

Cross breed 20

Dalmation 6

Siberian Husky 2

Large sized (26 kgs and

above)

Labrador retriever 142

German shepherd 52

Doberman 12

Golden retriever 8

Rottweiler 10

Great Dane 18

Mastiff 2

Saint Bernard 8

45

Figure3: Incidence in Large sized breeds

0

20

40

60

80

100

120

140

160 142

52

12 8 1018

28

Large sized breeds

46

4.2 CLINICAL SYMPTOMS

4.2.1 Pain

In group I during pre skeletal maturity period 33.33 per cent of dogs (two

nos) were with a pain score of four, 50.00 per cent of dogs (three nos) with a pain

score of three and 16.67 per cent of dogs (one no) with a pain score of two.

Whereas, during post skeletal maturity period 16.67 per cent of dogs were (one no)

with a pain score of four, 33.33 per cent of dogs (two nos) with a pain score of three

and 50 per cent of dogs (three nos) with a pain score of two. (Table 2)

In group II during pre skeletal maturity period 66.67 per cent of dogs (four

nos) were with a pain score of four and 33.33 per cent of dogs (two nos) with a pain

score of three. Whereas, during post skeletal maturity period 50.00 per cent of dogs

(three nos) with a pain score of four, 33.33 per cent of dogs (two nos) with a pain

score of three and 16.67 per cent of dogs (one no) with a pain score of two. (Table 2)

4.2.2 Lameness

In group I during pre skeletal maturity period 50.00 per cent of dogs (three

nos) were with a score of four, 33.33 per cent of dogs (two nos) with a score of three

and 16.67 per cent of dogs (one no) with a score of two. Whereas, during post

skeletal maturity period 16.67 per cent of dogs (one no) were with a score of four,

33.33 per cent of dogs (two nos) with a score of three and 50.00 per cent of dogs

(three nos) with a score of two. (Table 3)

In group II during pre skeletal maturity period 50 per cent of dogs (three nos)

were with a score of four, 33.33 per cent of dogs (two nos) with a score of three and

16.67 per cent of dogs (one no) with a score of two. Whereas, during post skeletal

maturity period 33.33 per cent of dogs (two nos) were with a score of four, 50.00 per

cent of dogs (three nos) with a score of three and 16.67 per cent of dogs (one no)

with a score of two. (Table 3)

47

Table 2

Pain scoring in Group I and Group II dogs during pre and post skeletal

maturity period

Dog

No

Group I Group II

Pre skeletal

maturity

period

Post skeletal

maturity

period

Pre skeletal

maturity

period

Post skeletal

maturity period

1 4 4 4 4

2 3 2 4 4

3 4 3 3 2

4 3 2 4 3

5 2 2 3 3

6 3 3 4 4

48

Table 3

Lameness scoring in Group I and Group II dogs during pre and post skeletal

maturity period

Dog

No

Group I Group II

Pre skeletal

maturity

period

Post skeletal

maturity

period

Pre skeletal

maturity

period

Post skeletal

maturity period

1 4 4 4 4

2 3 2 3 3

3 4 3 2 2

4 3 2 4 3

5 2 2 3 3

6 4 3 4 4

49

4.3. PHYSICAL PALPATION FINDINGS

4.3.1 Ortolani sign

In group I dogs, during pre skeletal maturity period 33.33 per cent of dogs(two nos) exhibited unilateral positive Ortolani sign, 33.33 per cent of dogs (twonos) exhibited bilateral positive Ortolani sign and the remaining 33.33 per cent ofdogs (two nos) did not show positive Ortolani sign. Whereas, during post skeletalmaturity period 16.67 per cent of dogs (one no) exhibited unilateral positive Ortolanisign, 33.33 per cent of dogs (two nos) exhibited bilateral positive Ortolani sign andthe remaining 50.00 per cent of dogs (three nos) did not show positive Ortolani sign.(Table 4)

In group II dogs, both during pre skeletal maturity period and post skeletalmaturity period 16.67 per cent of dogs (one no) exhibited unilateral positive Ortolanisign and the remaining 83.33 per cent of dogs (five nos) exhibited bilateral positiveOrtolani sign. (Table 4)


4.4.1 Haemoglobin

The mean haemoglobin (g/dl) values in group I during pre skeletal and postskeletal maturity period were 12.45±0.39 and 12.38±0.28 respectively (Table 5).Whereas, values in group II during pre skeletal and post skeletal maturity periodwere 12.00±0.28 and 12.48±0.28 respectively (Table 6).

No significant difference in haemoglobin values, (P<0.05) between preskeletal and post skeletal maturity period in Group I and Group II were observed.

4.4.2 Packed Cell Volume

The mean packed cell volume (percentage) values in group I during preskeletal and post skeletal maturity period were 33.78±2.55 and 33.66±2.46respectively (Table 5). Whereas, values in group II during pre skeletal and postskeletal maturity period were 33.38±2.02 and 32.51±2.81 respectively (Table 6).

No significant difference in packed cell volume values, (P<0.05) between preskeletal and post skeletal maturity period in Group I and Group II were observed.

50

Table 4

Ortolani sign in Group I and Group II dogs during pre and post skeletal

maturity period

Dog

No

Group I Group II

Pre skeletal

maturity

period

Post skeletal

maturity

period

Pre skeletal

maturity

period

Post skeletal

maturity period

1 Bilateral Bilateral Bilateral Bilateral

2 Unilateral Unilateral Bilateral Bilateral

3 Bilateral Bilateral Unilateral Unilateral

4 Negative Negative Bilateral Bilateral

5 Negative Negative Bilateral Bilateral

6 Unilateral Negative Bilateral Bilateral

51

4.4.3 Red Blood Cell count

Red blood cell count (millions/cumm) in group I during pre skeletal and post

skeletal maturity period were 5.47±0.21 and 5.57±0.18 respectively (Table 5).

Whereas, values in group II during pre skeletal and post skeletal maturity period

were 5.77±0.14 and 5.26±0.28 respectively (Table 6).

No significant difference in red blood cell count, (P<0.05) between pre

skeletal and post skeletal maturity period in Group I and Group II were observed.

4.4.4 White Blood Cell count

White blood cell count (per cumm) in group I during pre skeletal and post

skeletal maturity period were 14683.33±2033.78 and 15300±1926.30 respectively

(Table 5). Whereas, values in group II during pre skeletal and post skeletal maturity

period were 14950±1510.38 and 18375±2185.39 respectively (Table 6).

No significant difference in white blood cell count, (P<0.05) between pre


4.4.5 Neutrophils

Neutrophil count (percentage) values in group I during pre skeletal and post

skeletal maturity period were 83.33±0.84 and 80.33±1.84 respectively (Table 5).


were 77.67±0.62 and 79.67±1.02 respectively (Table 6).

No significant difference in neutrophil count, (P<0.05) between pre skeletal

and post skeletal maturity period in Group I and Group II were observed.

4.4.6 Lymphocytes

Lymphocyte count (percentage) values in group I during pre skeletal and

post skeletal maturity period were 16.83±1.57 and 17.83±1.53 respectively


period were 20.83±0.47 and 21.00±1.03 respectively (Table 6).

52

No significant difference in lymphocyte count, (P<0.05) between pre skeletal


4.4.7 Serum Alkaline Phosphatase

Serum alkaline phosphatase (IU/lit) values in group I during pre skeletal and

post skeletal maturity period were 165.81±10.08 and 165.48±13.34 respectively


period were 89.10±10.08 and 146.46±15.02 respectively (Table 6).

No significant difference in Serum alkaline phosphatase values, (P<0.05)

between pre skeletal and post skeletal maturity period in Group I and Group II were

observed.

4.4.8 Total Protein

Total protein (g/dl) values in group I during pre skeletal and post skeletal

maturity period were 6.35±0.20 and 6.76±0.16 respectively (Table 5). Whereas,

values in group II during pre skeletal and post skeletal maturity period were

6.72±0.17 and 6.57±0.09 respectively (Table 6).

No significant difference in total protein values, (P<0.05) between pre


4.4.9 Albumin

Albumin (g/dl) values in group I during pre skeletal and post skeletal




No significant difference in albumin values, (P<0.05) between pre skeletal


53

4.4.10 Calcium

Calcium (mg/dl) values in group I during pre skeletal and post skeletal




No significant difference in calcium values, (P<0.05) between pre skeletal


4.4.11 Phosphorus

Phosphorus (mg/dl) values in group I during pre skeletal and post skeletal




No significant difference in phosphorus values, (P<0.05) between pre


4.5 QUANTITATIVE RADIOGRAPHIC ASSESSMENT

4.5.1 Norberg angle

Of the twelve hips studied in Group I dogs during pre skeletal maturity

period, the Norberg angle was moderate in 58.33 per cent (90-105 degree) and 41.67

per cent (<90 degree) were severely dysplastic. Whereas, during post skeletal

maturity period 33.33 per cent (>105 degree) were normal, 50.00 per cent (90-105

degree) moderate and 16.67 per cent (<90 degree) severely dysplastic. (Table 7, 8)

Out of the twelve hips studied in Group II dogs during pre skeletal maturity

period, 100.00 per cent (<90 degree) were severely dysplastic. Whereas, during post

skeletal maturity period, 16.67 per cent (90-105 degree) were moderate and 83.33

per cent (<90 degree) were severely dysplastic. (Table 9, 10)

54

Table 5

Haematological and biochemical parameters in group I dogs

ParameterPre skeletal

maturity periodPost skeletal

maturity periodt-Test P-value

Haemoglobin(g/dl)

12.45±0.39 12.38±0.28 0.44 0.67

Packed cellvolume

(percentage)33.78±2.55 33.66±2.46 0.24 0.82

Red Blood Cell(millions/cumm)

5.47±0.21 5.57±0.18 0.62 0.56

White BloodCell (per cumm)

14683.33±2033.78 15300±1926.30 0.69 0.52

Neutrophils(percentage)

83.33±0.84 80.33±1.84 1.11 0.31

Lymphocytes(percentage)

16.83±1.57 17.83±1.53 0.68 0.52

Serum AlkalinePhosphatase

(IU/lit)165.81±10.08 165.48±13.34 0.10 0.92

Total Protein(g/dl)

6.35±0.20 6.76±0.16 1.55 0.18

Albumin (g/dl) 3.12±0.09 3.10±0.09 0.12 0.90

Calcium (mg/dl) 11.69±0.83 11.31±0.72 0.97 0.37

Phosphorus(mg/ dl)

5.61±0.58 5.52±0.49 0.69 0.52

55

Table 6

Haematological and biochemical parameters in group II dogs

ParameterPre skeletal

maturity periodPost skeletal

maturity periodt-Test P-value

Haemoglobin(g/dl)

12.00±0.28 12.48±0.28 0.69 0.52

Packed cellvolume

(percentage)33.38±2.02 32.51±2.81 1.10 0.32

Red Blood Cell(millions/cumm)

5.77±0.14 5.26±0.28 2.43 0.05

White BloodCell (per cumm)

14950±1510.38 18375±2185.39 0.62 0.56

Neutrophils(percentage)

77.67±0.62 79.67±1.02 1.21 0.27

Lymphocytes(percentage)

20.83±0.47 21.00±1.03 0.15 0.88

Serum AlkalinePhosphatase

(IU/lit)89.10±10.08 146.46±15.02 0.12 0.90

Total Protein(g/dl)

6.72±0.17 6.57±0.09 1.78 0.13

Albumin (g/dl) 2.30±0.09 2.67±0.10 0.10 0.92

Calcium (mg/dl) 10.84±0.42 15.49±0.83 0.94 0.31

Phosphorus(mg/ dl)

7.27±0.53 6.16±0.70 0.44 0.67

56

Mean ± Standard error of Norberg angle values in group I during pre skeletal

and post skeletal maturity period were 90.92±3.56 and 95.67±3.29 respectively.


were 85.00±0.71 and 82.83±1.66 respectively. (Table 11, 12)

Statistical analysis revealed high significance (0.01 level) in group I values

between pre skeletal and post skeletal maturity period with respect to Norberg angle.

Whereas, in group II no significant (0.05 level) change was found between pre

skeletal and post skeletal maturity period. (Table 11, 12)

4.5.2 Distraction index


period, 58.33 per cent (0.3-0.7) were moderate and 41.67 per cent (>0.7) were

severely dysplastic. Whereas, during post skeletal maturity period 16.67 per cent

(<0.3) were normal, 58.33 per cent (0.3-0.7) were moderate and 25.00 per cent

(>0.7) were severely dysplastic. (Table 7, 8)


period 100.00 per cent (>0.7) were severely dysplastic. Whereas, during post

skeletal maturity period 16.67 per cent (0.3-0.7) were moderate and 83.33 per cent

(>0.7) were severely dysplastic. (Table 9, 10)

Mean ± Standard error of DI values in group I during pre skeletal and post

skeletal maturity period were 0.63±0.05 and 0.54±0.06 respectively. Whereas,


0.75±0.009 and 0.78±0.01 respectively. (Table 11, 12)


between pre skeletal and post skeletal maturity period with respect to DI. Whereas,

in group II no significance (0.05 level) was found between pre and post skeletal

maturity period with respect to DI. (Table 11, 12)

57

4.5.3 Dorsolateral subluxation score


period 66.67 per cent (40-60 percentage) were moderate and 33.33 per cent (<40

percentage) were severely dysplastic. Whereas, during post skeletal maturity period

33.33 per cent (>60 percentage) were normal, 33.33 per cent (40-60 percentage)

were moderate and 33.33 per cent (<40 percentage) were severely dysplastic. (Table

7, 8)


period 100.00 per cent (<40 percentage) were severely dysplastic. Whereas, during

post skeletal maturity period 33.33 per cent (40-60 percentage) were moderate and

66.67 per cent (<40 percentage) were severely dysplastic. (Table 9, 10)

Mean ± Standard error of dorsolateral subluxation score values in group I

during pre and post skeletal maturity period were 43.41±4.05 and 48.24±4.42

respectively. Whereas, values in group II during pre and post skeletal maturity

period were 27.87±1.47 and 26.92±3.51 respectively. (Table 11, 12)


between pre skeletal and post skeletal maturity period with respect to DLSI.

Whereas, in group II no significance was observed between pre skeletal and post

skeletal maturity period. (Table 11, 12)

4.5.4 Central edge angle

Of the twelve hips studied in Group I dogs the central edge angle during pre

skeletal maturity period 91.67 per cent (6-16 degree) were moderate and 8.33 per

cent (<6 degree) were severely dysplastic. Whereas, during post skeletal maturity

period 50.00 per cent (>16 degree) were normal and 50.00 per cent (6-16 degree)

were moderately dysplastic. (Table 7, 8)

In Group II dogs the central edge angle during pre skeletal maturity period,

16.67 per cent (6-16 degree) were moderate and 88.33 per cent (<6 degree) were

severely dysplastic. Whereas, during post skeletal maturity period, 16.67 per cent

58

(>16 degree) were normal, 50.00 per cent (6-16 degree) were moderate and 33.33

per cent (<6 degree) were severely dysplastic. (Table 9, 10)

Mean ± Standard error of Central edge angle values in group I during pre

skeletal and post skeletal maturity period were 11.50±1.00 and 15.25±1.40

respectively. Whereas, values in group II during pre skeletal and post skeletal

maturity period were 5.58±1.02 and 8.25±1.37 respectively. (Table 11, 12)


between pre skeletal and post skeletal maturity period with respect to CEA.

Whereas, in group II also high significance (0.01 level) was found between pre

skeletal and post skeletal maturity period. (Table 11, 12)

4.5.5 Acetabular slope angle

In Group I dogs the acetabular slope angle during pre skeletal maturity

period 100.00 per cent (7-25 degree) was moderate. Whereas, during post skeletal

maturity period 50.00 per cent (<7 degree) were normal and 50.00 per cent (7-25

degree) were moderately dysplastic. (Table 7, 8)


period, 33.33 per cent (7-25 degree) were moderate and 66.67 per cent (>25 degree)

were severely dysplastic. Whereas, during post skeletal maturity period 16.67 per

cent (<7 degree) were normal, 50 per cent (7-25 degree) were moderate and 33.33

per cent (>25 degree) were severely dysplastic. (Table 9, 10)

Mean ± Standard error of acetabular slope angle values in group I during pre




Statistical analysis revealed no significance (0.05 level) in group I values

between pre skeletal and post skeletal maturity period with respect to ASA. In group

II also no significance (0.05 level) was found between pre skeletal and post skeletal

maturity period. (Table 11, 12)

59

4.5.6 Subluxation index

The subluxation index in Group I dogs during pre skeletal maturity period

was moderate in 58.33 per cent (0.3-0.5 degree) and severely dysplastic in 41.67 per

cent (>0.5 degree). Whereas, during post skeletal maturity period 16.67 per cent

(<0.3 degree) were normal, 58.33 per cent (0.3-0.5 degree) were moderate and 25.00

per cent (>0.5 degree) were severely dysplastic. (Table 7, 8)

Out of the twelve hips studied for subluxation index in Group II dogs during

pre skeletal maturity period 100.00 per cent (>0.5 degree) were severely dysplastic.

Whereas, during post skeletal maturity period 8.33 per cent (0.3-0.5 degree) were

moderate and 91.67 per cent (>0.5 degree) were severely dysplastic. (Table 9, 10)

Mean ± Standard error of subluxation index values in group I during pre





between pre skeletal and post skeletal maturity period with respect to SI. Whereas,

in group II no significance (0.05 level) found between pre skeletal and post skeletal

maturity period. (Table 11, 12)

4.6 CORRELATION BETWEEN QUANTITATIVE RADIOGRAPHIC

ASSESSMENT

4.6.1 Correlation between Quantitative Radiographic Assessment Techniques

in group I dogs during pre and post skeletal maturity period

Norberg angle negatively correlated with Distraction index and Subluxation

index with significant values (0.05 level) of 0.87, 0.89, 0.90 and 0.78 during pre and

post skeletal maturity period respectively. Whereas, Norberg angle positively

correlated with Dorsolateral subluxation index with highly significant values (0.01

level) of 0.95 and 0.91 during pre and post skeletal maturity period respectively.

(Table 13)

60

Table 7

Quantitative Radiographic measurements in group I dogs during pre skeletal

maturity period

Dog

NoHip NA DI DLSI CEA ASA SI

1R 68.00 0.86 21.10 6 22 0.67

L 69.00 0.88 21.25 5 24 0.79

2R 95.00 0.55 43.30 8 18 0.35

L 100.00 0.65 53.30 12 24 0.45

3R 82.00 0.80 35.00 10 22 0.70

L 88.00 0.72 30.00 13 20 0.60

4R 100.00 0.40 58.00 14 8 0.35

L 102.00 0.50 55.00 12 10 0.45

5R 100.00 0.40 58.00 14 8 0.35

L 104.00 0.32 60.00 15 9 0.30

6R 88.00 0.80 42.00 14 10 0.60

L 95.00 0.65 44.00 15 8 0.50

61

Table 8

Quantitative Radiographic measurements in group I dogs during post skeletal

maturity period

Dog no Hip NA DI DLSI CEA ASA SI

1Rt 75.00 0.80 23.40 7 20 0.60

Lt 78.00 0.82 22.20 6 23 0.65

2Rt 90.00 0.50 47.20 13 20 0.30

Lt 94.00 0.60 56.80 15 25 0.40

3Rt 90.00 0.75 39.00 12 24 0.65

Lt 98.00 0.60 37.00 16 23 0.50

4Rt 106.00 0.30 62.00 18 4 0.30

Lt 108.00 0.40 61.30 20 6 0.40

5Rt 107.00 0.28 64.00 18 5 0.20

Lt 110.00 0.20 68.00 20 4 0.20

6Rt 92.00 0.68 48.00 18 6 0.45

Lt 100.00 0.55 50.00 20 4 0.40

62

Table 9

Quantitative Radiographic measurements in group II dogs during pre skeletal

maturity period


1Rt 82.00 0.75 25.20 4 26 0.65

Lt 85.00 0.80 21.50 3 28 0.75

2Rt 88.00 0.72 28.00 5 24 0.68

Lt 86.00 0.75 25.00 4 26 0.72

3Rt 80.00 0.80 32.00 12 5 0.75

Lt 86.00 0.75 30.00 14 6 0.70

4Rt 87.00 0.75 38.00 5 26 0.70

Lt 85.00 0.72 35.00 4 28 0.60

5Rt 86.00 0.75 25.00 4 26 0.72

Lt 88.00 0.72 28.00 5 24 0.68

6Rt 85.00 0.80 21.50 3 28 0.75

Lt 82.00 0.75 25.20 4 26 0.65

63

Table 10

Quantitative Radiographic measurements in group II dogs during post skeletal

maturity period


1Rt 80.00 0.80 20.00 4 30 0.70

Lt 75.00 0.85 19.00 3 32 0.85

2Rt 82.00 0.78 20.00 8 22 0.75

Lt 84.00 0.80 16.00 9 23 0.78

3Rt 90.00 0.70 44.00 16 3 0.60

Lt 96.00 0.65 42.00 18 4 0.50

4Rt 83.00 0.78 42.00 8 24 0.72

Lt 83.00 0.73 45.00 9 25 0.65

5Rt 84.00 0.80 16.00 9 23 0.78

Lt 82.00 0.78 20.00 8 22 0.75

6Rt 75.00 0.85 19.00 3 32 0.85

Lt 80.00 0.80 20.00 4 30 0.70

64

Table 11

Paired `t`-Test in group I dogs during Pre and Post skeletal maturity period

QHATNo of

hips

Pre skeletal

maturity

period

Post skeletal

maturity

periodt -

Test

P –

ValueResult

Mean ±SE Mean ±SE

NA 12 90.92 3.56 95.67 3.29 3.25 0.00 **

DI 12 0.63 0.05 0.54 0.06 9.85 0.00 **

DLSI 12 43.41 4.05 48.24 4.42 8.14 0.00 **

CEA 12 11.50 1.00 15.25 1.40 6.63 0.00 **

ASA 12 15.25 1.99 13.67 2.70 1.91 0.08 NS

SI 12 0.51 0.04 0.42 0.04 7.49 0.00 **

NS : Statistically not significant (P > 0.05)

** : Statistically highly significant (P 0.01)

65

Table 12

Paired `t`-Test in group II dogs during Pre and Post skeletal maturity period

QHAT No of

hips

Group I Group II t -

Test

P –

Value

Result

Mean ±SE Mean ±SE

NA 12 85.00 0.71 82.83 1.66 1.17 0.26 NS

DI 12 0.75 0.00 0.78 0.01 1.38 0.19 NS

DLSI 12 27.87 1.47 26.92 3.51 0.40 0.69 NS

CEA 12 5.58 1.02 8.25 1.37 4.39 0.00 **

ASA 12 22.75 2.35 22.50 2.78 0.27 0.78 NS

SI 12 0.70 0.01 0.72 0.02 0.84 0.41 NS

NS : Statistically not significant (P > 0.05)

** : Statistically highly significant (P 0.01)

66

Distraction index negatively correlated with Dorsolateral subluxation index

with significant values (0.05 level) of 0.89 and 0.90 during pre and post skeletal

maturity period respectively. Whereas, Distraction index positively correlated with

Subluxation index with highly significant values (0.01 level) of 0.94 and 0.92 during

pre and post skeletal maturity period respectively. (Table 13)

The Dorsolateral subluxation index negatively correlated with Subluxationindex with significant values (0.05 level) of 0.88 and 0.87 during pre and postskeletal maturity period respectively. (Table 13)

4.6.2 Correlation between Quantitative Radiographic Assessment Techniquesin group II dogs during pre and post skeletal maturity period

Norberg angle negatively correlated with Distraction index, Subluxationindex and Acetabular slope angle with significant values of 0.93, 0.87 and 0.93 onlyduring post skeletal maturity period respectively. Whereas, Norberg angle positivelycorrelated with Central edge angle with significant value (0.05 level) of 0.96 onlyduring post skeletal maturity period. (Table 14)

Distraction index positively correlated with Subluxation index with highlysignificant values (0.01 level) of 0.83 and 0.95 during pre and post skeletal maturityperiod respectively. Whereas, Distraction index positively correlated withAcetabular slope angle with significant values (0.05 level) of 0.89 only during postskeletal maturity period and Distraction index negatively correlated with Centraledge angle with significant values (0.05 level) of 0.92 only during post skeletalmaturity period. (Table 14)

Subluxation index negatively correlated with Dorsolateral subluxation indexand Central edge angle with significant values (0.05 level) of 0.88 and 0.80 onlyduring post skeletal maturity period respectively. (Table 14)

Central edge angle negatively correlated with Acetabular slope angle withhighly significant values (0.01 level) of 0.98 and 0.97 during pre and post skeletalmaturity period respectively. (Table 14)

67

Table 13

Correlation between Quantitative Radiographic Assessment Techniques in

group I dogs during pre and post skeletal maturity period

QHAT

NA DI DLSI CEA ASA SI

Pre Post Pre Post Pre Post Pre Post Pre Post Pre Post

NA 1 1 -0.87 -0.90 0.95 0.91 0.78 0.92 -0.65 -0.70 -0.89 -0.78

DI 1 1 -0.89 -0.90 -0.61 -0.76 0.69 0.70 0.94 0.92

DLSI 1 1 0.74 0.86 -0.70 -0.68 -0.88 -0.87

CEA 1 1 -0.76 -0.76 -0.60 -0.72

ASA 1 1 0.63 0.66

SI 1 1

68

Table 14

Correlation between Quantitative Radiographic Assessment Techniques in

group II dogs during pre and post skeletal maturity period

QHAT

NA DI DLSI CEA ASA SI

Pre Post Pre Post Pre Post Pre Post Pre Post Pre Post

NA 1 1 -0.48 -0.93 -0.09 0.61 -0.22 0.96 0.32 -0.93 -0.02 -0.87

DI 1 1 -0.43 -0.77 0.13 -0.92 -0.23 0.89 0.83 0.95

DLSI 1 1 0.38 0.65 -0.30 -0.62 -0.38 -0.75

CEA 1 1 -0.98 -0.97 -0.18 -0.80

ASA 1 1 -0.27 0.78

SI 1 1

69

Discussion

69

CHAPTER V

DISCUSSION

5.1 INCIDENCE

5.1.1 Age

Dogs in the age group of less than one year of age had higher incidence of

hip dysplasia (46.27 per cent) when compared to dogs in the age group between one

to six years of age (31.67 per cent) and dogs in the age group of more than six years

of age (22.04 per cent). The increase in incidence in young animals less than one

year might be due to early rapid growth, disproportionate skeletal and muscular

growth, overloading of articular areas and tearing or stretching of round ligament

resulting in dysplasia. These findings concurred with the observation of Bennett and

May (1995), Kasstrom (1975) and Maki et al. (2004).

5.1.2 Sex

In this study, male dogs had higher incidence of hip dysplasia (57.45 per

cent) than female dogs (42.54 per cent). Priester and Mulvihill (1972) recorded

equal distribution of incidence of hip dysplasia in male and females. The increase in

incidence in male dogs may probably be due to the smaller number of population

studied or preference of the pet owners for male dogs higher in the studied

population. (Corley and Keller, 1989)

5.1.3 Size of the animal

Among the 322 dogs studied, highest incidence of canine hip dysplasia was

seen in large breeds of dogs (78.26 per cent), followed by small sized dogs (13.04

per cent) and medium sized dogs (8.69 per cent). This might be due to rapid growth

and early weight gain in large breed dogs (Genevois et al., 2008) resulting

insufficient relative strength for the hip muscles to prevent subluxation of the hip

joint during weight bearing. These findings concurred with, Alexandar (1992), Lust

and Summers (1981), Lust et al. (1985) and Riser (1975).

70

5.1.4 Breed

Of the 322 dogs studied, highest incidence of canine hip dysplasia was seen

in Labrador retrievers (44.09 per cent) than German shepherd dogs (16.14 per cent).

The increase in the incidence of dysplasia in Labrador retrievers might be due to

genetic predisposition (Chase et al., 2004 and Shepherd, 1986), anatomically

shallow acetabulum, early rapid weight gain (Barr et al., 1987), and loose skin,

heavy rounded stocky conformation (Fries and Remedios, 1995) with less developed

muscle and more than 10 per cent of subcutaneous fat (Hazewinkel, 1989) . Similar

observations were recorded by Riser et al. (1985) and Scartazzini (1970).

5.2 CLINICAL SYMPTOMS

5.2.1 Pain

In Group I, three animals showed improvement in pain score and in Group

II, two animals showed improvement in pain score. This might be due to

neutraceuticals administered (Belfield, 1976 and Bennett, 1987) during the skeletal

maturity period would have likely helped in alleviating the pain associated with HD

(Farrell et al., 2007 and Vezzoni et al., 2008). Also management advice given

during the skeletal maturity period such as restricted exercise and feeding (Kealy et

al., 1992; Kealy et al., 1993 and Kealy et al., 2000), confining puppies in a cage,

stay seated for long time in abduction-flexion position, to support the forced hip

congruence would have also helped in improvement in pain score. Manley et al.

(2007) and Vezzoni et al. (2008) reported similar findings in their study of hip

dysplasia.

5.2.2 Lameness

Four animals in group I and one in group II showed improvement in

lameness score. The improvement in lameness score in animals in both the groups

may be attributed to increased pelvic muscle mass (Smith, 1998), decrease in hip

laxity (Corley, 1992) and decreased pain during the developmental stage (Fry and

Clark, 1992). Less severe degree of dysplasia in the animals presented in group I

71

might be the contributing factor for the increased improvement in the lameness score

in this group during the skeletal maturity period. The findings of this study

concurred with that of Cardinet et al. (1997), Greg Keller (2006) and Newton

(1985).

5.3 PHYSICAL PALPATION BY ORTOLANI MANOEUVER

Persistence of positive Ortolani sign in group I and group II animals both the

period of assessment and an improvement or absence of Ortolani sign in one animal

in group I might be due to decrease in joint laxity. Ortolani sign showed correlation

with Norberg angle (Bardens and Hardwick, 1968) and Distraction index values of

respective animals in both groups. This finding concurred with Adams et al. (2000)

who noticed a significant relation between Ortolani maneuver results and

radiographic distraction index. (Puerto et al., 1999)


No significant difference was observed in haematological and biochemical

parameters among Group I and Group II animals between pre and post skeletal

maturity period. This probably might be due to slow onset of hip dysplasia which

could not have produced any effect on reticulo-endothelial system and biochemical

values. These findings are in concurrence with the study of Hansen (1989), Lust et

al. (1973) and Lust et al. (1993).

5.5 QUANTITATIVE RADIOGRAPHIC MEASUREMENTS

5.5.1 Norberg angle

Highly significant increase in mean Norberg angle values were noticed

between pre and post skeletal maturity in group I. In group II there was non

significant decrease in the mean Norberg angle values found between pre and post

skeletal maturity period. All hips in group I except two, irrespective of the severity

showed improvement in Norberg angle values. In group II, Norberg angle values in

all hips except two showed a decrease.

72

The improvement in Norberg angle values in group I might be due to

anatomically developed moderately deep acetabulum in German shepherd breeds of

dogs (Scartazzini, 1970), increased ossification centers during the developmental

stage (Cardinet et al., 1997), increased pelvic muscle mass (Greg Keller, 2006) and

fibrosis and thickening of the joint capsule of the coxofemoral joint. (Janutta and

Distl, 2006 and Janutta et al., 2008)

The decrease in Norberg angle values in group II might be due to

anatomically shallow acetabulum in Labrador retriever breeds of dogs (Scartazzini,

1970), early rapid weight gain which led to abnormal weight bearing forces across

the joint (Kasstrom, 1975) and loose skin, heavy rounded stocky conformation with

less developed muscle and more than 10 per cent subcutaneous fat (Lust et al.,

1992).

5.5.2 Distraction Index

The mean DI value of German shepherd breeds of dogs in group I had highly

significant decrease noticed from pre skeletal maturity period to post skeletal

maturity period. Appreciable decrease of DI was noticed on all animals in this

group. But in Group II there was no significant increase in DI values were seen in

post skeletal maturity period. Distraction index is the indicative of passive joint

laxity (Gibbs, 1997) which allows the femoral head move away from the articular

surface of the acetabulum and responsible for development of degenerative joint

disease in dogs. (Ginja et al., 2008a; Ginja et al., 2008b and Ginja et al., 2008c)

In group I improvement in DI values during post skeletal maturity period

might be due to increased ossification (Hazewinkel et al., 1991) of moderately deep

acetabulum in German shepherd breeds of dogs (Scartazzini, 1970). Whereas, in

Labrador retriever breeds of dogs in Group II even though skeletal muscle mass

development and muscular tone contributed for increase in DI (Lust et al., 1993), the

genetically shallow acetabulum (Scartazzini, 1970) and unique early rapid weight

73

gain (Silvestre et al., 2007) for the breed characteristic would have caused negative

effect resulted in non significant raise in DI values.

5.5.3 Dorsolateral Subluxation Score

DLSI value that is percentage of acetabular coverage in weight bearing

position (Farese et al., 1999) increased in all animals in group I from pre skeletal

maturity period to post skeletal maturity period. More increase in acetabular

coverage in dogs with upper limit of moderate values, which became normal that is

more than 60 percentage. This might be due to progressive strength of supporting

soft tissue structures namely joint capsule and muscle mass (Popovitch et al., 1995)

and also gradual deepening of acetabulum during the development in German

shepherd breeds (Mackenzie et al., 1985) of dogs. This finding concurred with

Hazewinkel (1994).

In group II the animals with DLSI values below 30 percentage in pre skeletal

maturity period reduced further during the skeletal maturity period. This might be

due to rapid weight gain due to increased fat percentage and shallow acetabulum

during skeletal maturity period would have allowed dorsolateral movement of the

femoral head during weight bearing. This finding concurred with Smith et al.

(1990).

5.5.4 Central edge angle and Acetabular slope angle

All dogs in group I and II except dog no 1 and 6 in group II showed increase

in CEA and ASA values during skeletal maturity period. The animals in both the

group which were severely dysplastic retained the CEA and ASA values during

skeletal maturity period. Since CEA and ASA indicative of damage to the dorsal

acetabular rim (Morgan, 1987) and have no effect on the hip laxity which is the

definitive reason for development of hip dysplasia in dogs. This finding concurred

with Meomartino et al. (2002) and Risler et al. (2009).

74

5.5.5 Subluxation index

SI that is displacement of femoral head from the acetabulum during dorsally

directed manual force (Olsson, 1961) decreased in all animals in group I (German

shepherd dogs) during skeletal maturity period. But in Labrador retriever breeds of

dogs the laxity was more in all animal except one hip in one animal. Even though

subluxation of femoral head depends on dorsally applied pressure, recoiling effect of

supporting structure of the hip joint especially elasticity of the joint capsule, strength

of the muscle mass, surface area of the dorsal acetabulum plays a major role in

opposing the manual pressure. The difference in strength in those structures in group

I and group II animals might be the reason for the difference in the values. This

finding concurred with Fluckiger et al. (1999).

5.6 CORRELATION BETWEEN DIFFERENT QUANTITATIVE

RADIOGRAPHIC ASSESSMENT TECHNIQUES

The negative correlation between NA and DI (r 0.8) suggests that Norberg

angle and DI has a strong relation. An increase in Norberg angle correspondingly

shows a decrease in DI percentage denoting good hip and decreasing Norberg angle

and increasing DI denoting susceptibility to dysplastic hip.

The positive correlation between NA and DLSI (r 0.8) suggests that as

Norberg angle and DLSI has a strong relation. An increase in Norberg angle

correspondingly shows an increase in DLSI percentage denoting good hip and

decreasing Norberg angle and decreasing DLSI denoting susceptibility to dysplastic

hip.

The negative correlation between NA and SI (r 0.8) suggests that as

Norberg angle and SI has a strong relation. An increase in Norberg angle

correspondingly shows a decrease in SI percentage denoting good hip and

decreasing Norberg angle and increasing SI denoting susceptibility to dysplastic hip.

75

The negative correlation between DI and DLSI (r 0.8) suggests that as DI

and DLSI has a strong relation. An increase in DI correspondingly shows a decrease

in DLSI percentage denoting dysplastic hip and decreasing DI and increasing DLSI

denoting good hip.

The positive correlation between DI and SI (r 0.8) suggests that as DI and

SI has a strong relation. An increase in DI correspondingly shows an increase in SI

percentage denoting dysplastic hip and decreasing DI and decreasing SI denoting

good hip.

The negative correlation between DLSI and SI (r 0.8) suggests that as

DLSI and SI has a strong relation. An increase in DLSI correspondingly shows a

decrease in SI percentage denoting good hip and decreasing DLSI and increasing SI

denoting dysplastic hip.

Displacement or subluxation of femoral head away from acetabular cavity

was measured through different quantitative radiographic assessment techniques

after application of external forces (Heyman et al., 1993). In Norberg angle

measurement position recoiling effect of winding of joint capsule pushes the femoral

head and maintains it in congruence with acetabulum. In DI laterally directed force

over the femoral head luxates it from the acetabular cavity if the supporting soft

tissue structures were week. Dorsally directed force towards the acetabulum in DLSI

and SI luxate the femoral head, in reduced contact surface area of the acetabulum

and weekend supporting soft tissue structures around the hip joint. ASA and CEA

reveal the dorsal acetabular coverage surface area over the femoral head when there

were no externally applied forces. (Ginja et al., 2009)

More relative correlation was seen between NA to DLSI and DI to SI. DI

highly correlates with SI in both groups. Values which were normal and near

normal, highly correlates with each others in all quantitative radiographic

assessment methods. This indicates stronger supporting structures around the hip

joint in normal anatomical alignment overcome the external pressure and maintains

the femoral head in congruence with the acetabulum.

76

Defects either hereditary or acquired in any one of the structures like shallow

acetabulum, weekend joint capsule, poor muscular development and rapid weight

gain before the skeletal maturity might fail to resist the external forces. Failure in

different structures deviate the normal value of quantitative assessment procedure

like week joint capsule and reduced muscle mass affects the NA and DI, decreased

dorsal surface area of the acetabulum cover affects the DLSI and SI. These were the

reasons most probably occurred in Labrador retriever breeds of dogs where the

quantitative hip assessment values were not effectively correlated with each other as

seen with German shepherd breeds of dogs. There were no significant correlation

between CEA and ASA with other methods since defects in dorsal acetabular

coverage happened during later stage of the disease progress like enthesophyte

formation and bony remodeling which leads to the OA and DJD. (Johnson et al.,

1998; Powers et al., 2004 and Szabo et al., 2007)

Culp et al. (2006) noticed linear correlation between NA and DI in all breeds

of dogs and also found a high correlation in animals with normal values of NA and

DI.

Farese et al. (1998) found high correlation between DLSI and DI in

predicting OA susceptibility in dogs. DI value of 0.3 and DLSI value of 64.00±1.5

were proved to be unsusceptible to OA. Because it produces least passive laxity. DI

value of 0.7 and DLSI value of 39.00±2.6 had high probability of developing OA.

(Smith et al., 1995)

Fluckiger (1995) stated that most of the stress study reveals that positive

correlation between the coxofemoral joint laxity and coxarthrosis. The author also

noted 87 percentage of Labrador retriever with the DI value of less than 0.4 at the

age of 4 months developed normal hips and 57 percentage of dog with DI value

greater than 0.4 became dysplastic. He also noticed high correlation between DI and

SI, since both the techniques dislocate the hip when using differently directed

external forces.

77

Summary

77

CHAPTER VI

SUMMARY


Orthopedic unit of Madras Veterinary College Teaching Hospital were selected for

the study. Clinically hip dysplastic German shepherd and Labrador retriever breeds

of dogs were grouped into two groups of six numbers in each groups and subjected

to hip assessment before and after skeletal maturity of long bones.

Under general anesthesia radiography was performed in different positioning

methods namely, Standard Ventro dorsal view(SVDV), Distraction view(DV),

Weight bearing view, Dorsal acetabular rim view and 60 degree stress view. From

these positioning methods, six different quantitative measurements of hips were

taken to grade the hips for dysplasia namely Norberg angle, Distraction index,

Dorsolateral subluxation index, Acetabular slope angle, Central edge angle and

subluxation index.

The clinical signs, physical palpation by Ortolani manouver and haemato-

biochemical parameters were studied and found that in group I and group II dogs

there was an improvement in pain score during skeletal maturity period whereas

Lameness score was improved only in group I dogs.

No significant difference observed in Hematological and Biochemical

Parameters among Group I and Group II animals between pre and post skeletal

maturity period.. Correlation between the Quantitative radiographic measurements

were showed that high correlation between NA and DLSI, DI and SI. More relative

correlation was seen between NA to DLSI and DI to SI. DI highly correlates with SI

in both groups. Values which were normal and near normal highly correlates with

each others in all quantitative radiographic assessment methods.

Defects either hereditary or acquired in any one of the structures like shallow

acetabulum, weekend joint capsule, poor muscular development and rapid weight

gain before the skeletal maturity might fail to resist the external forces and deviate

78

the normal value of quantitative assessment procedures. Week joint capsule and

reduced muscle mass affects the NA and DI, decreased dorsal surface area of the

acetabulum cover affects the DLSI and SI. Those were the reasons most probably

occurred in Labrador retriever breeds of dogs where the quantitative hip assessment

values were not effectively correlated with each other as seen with German shepherd

breeds of dogs. Since both CEA and ASA represent dorsal acetabular coverage,

there was no significant correlation seen between these values in both groups. As

there was no defects in dorsal acetabular coverage noticed which usually happened

during later stage of the disease progress due to enthesophyte formation and bony

remodeling which leads to the OA and DJD. No significant correlation was noticed

between CEA and ASA with other quantitative assessment methods.

79

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