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WBFSH Seminars 2009
Growth of bone tissue
Animal hospital data for studies of osteochondrosis
and osseus fragments of Swedish Warmblood horses
Photo: Göran Dalin
L.
Jönsson1,
G.
Dalin2,
A. Egenvall3, A.Näsholm1, L. Roepstorff2 and J. Philipsson1
1Dept.
Financed by:
of Animal Breeding and Genetics
2Dept. of Equine Sciences
3Dept of Clinical Sciences
Swedish University of Agricultural Sciences
Normal vs. abnormal growth
Foto: Göran Dalin
Foto: Göran Dalin
Foto: Göran Dalin
Why conduct study?
• 60-70 % of culled riding horses have locomotion
disturbance, e.g. osteochondrosis (OC)
• OC can result in lameness and/or loss in value
of the horse
• Animal hospital data is the only source of
information, except for specific scientific studies
• The heritability of OC in the Swedish
Warmblood has not yet been studied
Horses included in the study
• Radiographic limb examination at an animal hospital
in Sweden, in years 1992-1998, age 0.5 – 22 years
1) Horses with clinical signs e.g. lameness
n = 3639 (2651 with pedigree)
2) Normal horses examined:
• break-in
• prior to sale
• export
• breeding evaluation
n = 879 (724 with pedigree)
Photo: Göran Dalin
Photo: Göran Dalin
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Identification number
Documented data at Helsingborg Animal hospital
Screened horses
(Sales horses/breeding evaluation)
Clinically affected horses
Examination date
Horse-unique examination number
Name
Year of birth
Radiographic results
Father
Maternal grandfather
Examination date
Horse-unique examination number
Name
Year of birth
Radiographic results
Father
Maternal grandfather
Gender
• Less errors
• Easier to use in large
datasets
Photo: Flyinge
• UELN - world unique
Foto: Göran Dalin
Studied sites
Prevalence
Photo: Göran Dalin
Clinical horses
OC total: Finding in one
or several of the stifle,
hock and DOF in fetlock
Stifle
Hock
DOF:
Dorsal
Osseus
Fragment
POF:
Palmar/plantar
Osseus
Fragment
Screened horses
Pooled data
n
%
n
%
n
%
2651
10.9
724
18.9
3199
12.5
OC, stifle
1106
11.9
709
3.4
1734
8.5
OC, hock
1146
6.6
714
6.7
1785
6.2
DOF, fetlock
1347
7.0
686
11.4
1932
8.5
POF, fetlock
1347
10.7
686
13.7
1932
11.2
OC, total
a
a
Finding in one or several of the stifle, hock and DOF in fetlock
Illustration from Sandgren et al. 1993, Eq Vet J Suppl 16 pp. 31-37
Genetic analysis
Analysis 1:
o
o
o
o
Stifle
Hock
DOF fetlock
POF fetlock
Analysis 2:
o OC total
Factor in model:
year of examination
Heritability, observed scale
OC total:
0.05 (se = 0.03)
Factor in model:
year of examination
h² = 0,03 - 0,13
0.03
(se = 0.04)
0.08
(se = 0.04)
OC
0.13
(se = 0.04)
(se = 0.05)
Illustration from Sandgren et al. 1993, Eq Vet J Suppl 16 pp. 31-37
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0.10
Threshold
Heritability, underlying quantitative scale
OC total:
0.13 (se = 0.07)
Relationship between findings in
different locations
OC, stifle
h² = 0,09- 0,38
0.09
(se = 0.11)
0.32
0.32
(se = 0.12)
(se = 0.16)
0.05
0.06
0.01
OC, hock
DOF, fetlock
POF, fetlock
0.31 0.55
0.92 0.59
- 0.07 0.35
0.30 0.47
- 0.26 0.29
0.33 0.28
0.02
0.05
- 0.04
Genetic correlations above diagonal
Phenotypic correlations below diagonal
(se = 0.16)
0.38
OC, stifle
OC, hock
DOF, fetlock
POF, fetlock
Continuous distribution
Illustration from Sandgren et al. 1993, Eq Vet J Suppl 16 pp. 31-37
Use of animal hospital data
• Selected animals?
• Recording & documentation of diagnoses
– Document results of each examined joint
– Specify • degree/character of lesion
• position within joint and in which limb
• possible history of lameness and
cause of radiologic examination
• Identification of horses linked to diagnosis
– Identification number checked and documented
• Ideally:
• central documentation
• standardised classification of severity
• standardised radiographic projections
Localization
h2
SE
n
Breed & Age
Analysis
Author
OC hock
OC hock
0.243
0.273
0.19
0.08
793
793
Standardbred, 11-24 months
“
(Philipsson et al., 1993)
“
OC hock
OC hock
0.343
0.263
0.14
793
325
“
Standardbred, 18-24 months
LSM, DL
χ² hetero,
DL
SOR
STM
OC hock
OCD1
OCD1
OCD1
OCD1
OCD1
OCD1
OCD1
OCD1
OCD1
OCD distal
fetlock2
OCD proximal
fetlock2
OCD hock
OC hock
OC hock
OCD fetlock2
OC hock
0.523
0.064
0.074
0.583
0.453
0.643
0.343
0.193
0.143
0.093
0.233
0.04
0.03
0.15
0.23
0.06
0.02
0.23
0.24
0.07
644
2407
3566
144
401
401
456
144
350
350
3725
Standardbred, 6-21 months
Germ. Rid. Horses, 3-8 years
“
Germ. Rid. Horses, 6-24 months
“
“
“
“
Maremano horses, 2-3 years
“
Hanoverian Warmblood, all ages
STM
LSM
LAM
LSM, DL
LSM, DL
STM
ATM
ATM
LAM, DL
ATM
LAM, DL
(Gröndahl and Dolvik, 1993)
(von Winter et al., 1996)
“
(von Willms et al., 1999)
“
“
“
“
(Pieramati et al., 2003)
“
(Stock et al., 2005)
0.603
0.21
3725
“
LAM, DL
0.403
0.303
0.333
0.143
0.043
0.06
0.04
0.06
0.03
0.07
3725
3748
5102
5102
167
LAM, DL
LAM, DL
LAM, DL
LAM, DL
LAM, DL
“
(Stock and Distl, 2006a)
(Stock and Distl, 2007)
“
(Wittwer et al., 2007)
0.163
0.483
0.333
0.103
0.003
0.233
0.363
0.053
0.143
0.16
0.28
0.19
0.14
0.00
0.09
0.11
0.05
0.08
167
167
152
152
152
811
811
811
811
“
Hanoverian Warmblood, all ages
Hanoverian Warmblood, 3-6 year
“
South German Coldblood, all
ages
“
“
German Warmblood, 9 & 21 mo
“
“
Dutch Warmblood, 1 year
“
“
“
LAM, DL
LAM, DL
LAM, DL
LAM, DL
LAM, DL
LAM, DL
LAM, DL
LAM, DL
LAM, DL
“
“
(Walker et al., 2008)
“
“
(Van Grevenhof et al., 2009)
“
“
“
OC fetlock*
POF
OC/OCDhock
OC/OCDstifle
OC/OCDfetlock2
OC /OCDanimal
OC/OCD hock
OC/OCD stifle
OC/OCD fetlock2
Conclusions
• Animal hospital data can be used for genetic studies of
OC and POF.
• There is a significant genetic variation of OC and POF,
predominantly for lesions in the hock and fetlock.
• Recommended to consider all OC lesions (all joints) in
breeding programs; positive correlations present, in
particular between DOF & stifle OC.
• POF should preferably be selected against due to
highest prevalence and heritability and the decrease in
value of an affected horse. Although, it does not
necessarily cause lameness.
“
(Schougaard et al., 1990)
“
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