Genetic analyses of elbow and hip dysplasia in German shepherd dogs

177 Pages·2005·2.96 MB·English

Aus dem Institut für Tierzucht und Vererbungsforschung
der Tierärztlichen Hochschule Hannover

Genetic analyses of elbow and
hip dysplasia in German shepherd dogs

INAUGURAL-DISSERTATION
zur Erlangung des Grades einer
DOKTORIN DER VETERINÄRMEDIZIN
(Dr. med. vet.)
durch die Tierärztliche Hochschule Hannover

Vorgelegt von
Verena Janutta
aus Wuppertal

Hannover 2005
Wissenschaftliche Betreuung: Univ.-Prof. Dr. Dr. habil. Ottmar Distl

1. Gutachter: Univ.-Prof. Dr. Dr. habil. Ottmar Distl
2. Gutachter: Univ.-Prof. Dr. Helmut Waibl

Tag der mündlichen Prüfung: 24.05.2005
Dedicated to my family.
Parts of this study were accepted by or submitted to the following journals:

Animal Science
Deutsche tierärztliche Wochenschrift
Journal of Heredity
Journal of Small Animal Practice
Journal of Veterinary Medicine A
Contents

CHAPTER 1
Introduction 1

CHAPTER 2
Canine elbow dysplasia – a review 5

CHAPTER 3
Review of the inheritance of canine hip dysplasia 31

CHAPTER 4
Genetic analysis of three different classification protocols in the evaluation of
elbow dysplasia in German shepherd dogs 51

CHAPTER 5
Genetic evaluation of elbow angles as predictors of elbow dysplasia (ED) in
German shepherd dogs 75

CHAPTER 6
Genetic trends of canine hip dysplasia (CHD) in the German population of
German shepherd dogs 99

CHAPTER 7
Complex segregation analysis of canine hip dysplasia in German shepherd dogs 123

CHAPTER 8
General discussion 143

CHAPTER 9
Summary 155

CHAPTER 10
Zusammenfassung 159
Table of abbreviations

-2lnL -2 log likelihood
AIC information criterion of Akaike (1974)
ANOVA analysis of variance
b regression coefficient
BLUP best linear unbiased prediction
BV breeding value
CHD canine hip dysplasia
DF/d.f. degrees of freedom
DI hip distraction index
DLS dorsolateral subluxation score
ED elbow dysplasia
ED-SV elbow dysplasia score according to IEWG protocol
ED-LA elbow dysplasia score according to Lang et al. (1998)
ED-TH elbow dysplasia score according to Tellhelm (2003)
e residual effect, comprising all effects not explained by the other
effects in the model
et al. et alii
FCI Fédération Cynologique Internationale
FCP fragmented coronoid process
Fig. figure
FS full-sibs
F F-value
GLM general linear model
GS Gibbs sampling
GSD German shepherd dog
h2 heritability
H III Henderson’s method III
HD Hüftgelenkdysplasie
hw Hardy-Weinberg equilibrium assumed
IEWG International Elbow Working Group
IPA Isolierter Processus anconaeus
LA1 – LA7 different radiographic criteria according to Lang et al. (1998)
LAM linear animal model
LS least squares
LSM least square means
MCMC Markov-Chain Monte Carlo
MHS maternal half-sibs
ML maximum likelihood
MTGSAM multiple trait Gibbs sampler for animal models
N/n number
nhw no Hardy-Weinberg equilibrium assumed
OCD osteochondrosis dissecans
OFA Orthopedic Foundation for Animals
OL angle reflecting the inclination of the olecranon towards the axis of the
radius
OSS age at onset of ossification of the femoral head
P/p error probability
PA angle describing the cranial protrusion of the anconeal process
PEST multivariate prediction and estimation
PHS paternal half-sibs
QTL quantitative trait loci
r correlation coefficient
r additive genetic correlation coefficient
g
r residual correlation coefficient
e
R2 coefficient of determination
RA angle enclosing the joint-forming part of the radius
RBV relative breeding value
REML residual maximum likelihood
RgA regression analysis
RZW Relativzuchtwert
S.A.G.E. statistical analysis for genetic epidemiology
SAS statistical analysis system
SD/s.d. standard deviation
SE standard error
σ 2 additive genetic variance
a
σ 2 residual variance
e
σ 2 permanent environmental variance of the kennel
k
σ2 permanent environmental variance of the litter
l
σ 2 additive genetic maternal variance
m
σ 2 phenotypic variance
p
SV German Shepherd Dog Breeding Association
Tab. table
TH1 – TH7 different radiographic criteria according to Tellhelm (2003)
UAP ununited anconeal process
UL angle circumscribing the extension of the olecranon and a part of the
trochlear notch of the ulna
VCE variance component estimation
x mean value
χ2 chi square
Introduction

CHAPTER 1

Introduction

1
Introduction
Introduction

Canine elbow dysplasia (ED) and canine hip dysplasia (CHD) are widespread skeletal
diseases in many dog breeds. These degenerative joint diseases are characterised by
conformational changes in the affected joints, and can result in clinical lameness and
considerable impairment of the dog.
ED includes different primary lesions: fragmented coronoid process (FCP), ununited anconeal
process (UAP), osteochondrosis dissecans of the trochlea humeri, and incongruency of the
elbow joint (INC). German shepherd dogs were often reported as affected by ED in clinical
studies or single case reports. Population based analyses regarding occurrence and distribution
of ED and its single primary lesions so far were mainly accomplished for breeds other than
German shepherd dogs. Radiographs of the elbows are voluntarily performed in German
shepherd dogs and so unfavourable screening results have no consequences for breeding
license of dogs. Only a few kennel clubs have started to analyse prevalences, affection status
and kind of primary lesions among their dogs, but as evaluation of ED is complicated by
different primary lesions with different aetiology and variable age of onset, different
evaluation schemes have been developed and are currently discussed with respect to their
usefulness in the different breeds. Therefore, one task of the present thesis is to compare
different evaluation schemes proposed so far in literature. Three different scoring systems
evaluating radiological structures and radiographic signs of ED and a system using elbow
angle measurements should be compared for their use in breeding programmes against elbow
dysplasia in German shepherd dogs. Especially the evaluation system using elbow angles as
predictors for ED should be tested, as it is intensely promoted and lively discussed on the
internet, though few publications are available on this topic. The elbow angle measurements
will be evaluated with respect to genetic parameters and prediction of breeding values for the
selection of dogs that are not susceptible to elbow dysplasia. Reports on Swiss Labrador
Retrievers as well as Finnish Rottweilers, Bernese mountain dogs and Labrador Retrievers
showed positive phenotypic and genetic correlations between CHD and ED, while for Finnish
Golden Retrievers and German shepherd dogs genetic correlations were low and negative or
about zero. Therefore, genetic and residual correlations between CHD and ED should be
examined in the present population of German shepherd dogs in Germany. Selection
programmes regarding the hip dysplasia status of the dogs were introduced for the German
shepherd dog as early as 1966 by the German Shepherd Dog Breeding Association (SV) using
mass selection according to the dog’s own CHD status, and later on using breeding values for
2