Genetic Diseases of German Shorthaired Pointer Dogs

Report
Genetic Diseases
of
German Shorthaired
Pointer Dogs
James C. Zgoda, M.S.,
D.V.M.
Otterkill Animal Hospital
Campbell Hall, NY
Sleepy Hollow GSHP Club
July 21, 2010
PHENOTYPE
Phenotypic Testing
• Conformation Shows/Testing
▫ Meet Breed Standard
• Screening Organizations
▫ OFA
▫ PennHip
▫ CERF
GENOTYPE
• Genetic makeup of
animal
•Not all genes are
expressed
•Many factors are
involved
Genetic Testing
• Screen for actual presence of Gene
or Gene marker
• Need to be verified for each breed
• Proprietary technique
▫ Results in Many Testing Centers
▫ Cheek swabs or blood used to
collect DNA
▫ Must minimize contamination
Terminology
• Hereditary/Inherited/ Heritable
▫ Traits are passed on from
generation to generation via genes
• Congenital
▫ Traits present at birth but may not
be hereditary, e.g. birth defects
Phenotypic Testing
• Advantages
▫ It’s what we’re all used to
▫ Has been used for long time
▫ Breed standards
• Disadvantages
▫ Harmful traits may be passed along with
good ones
▫ May take long time for problem to
become apparent
▫ Screening tests are subjective
Genotypic Testing
• Advantages
▫ Results can be known at very early
age
▫ Ease of testing
▫ Screening tests are objective
▫ Definitively know genetic status
• Disadvantages
▫ Multiple Laboratory sites
▫ Tests limited
▫ Must be verified for each specific
breed
Gene Expression
•Dominant
• Gene will be
expressed if only
1 copy of gene
present
•Recessive
• Gene will be
expressed only if
2 copies of gene
are present
• Incomplete/variable
expression
• Gene may not be
fully expressed as
expected
• Results in “sliding
scale” of traits
The Old Punnett
Square
GSHP Inherited
Diseases
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Hip/Elbow Dysplasia
Acral Multilation Syndrome
Aortic Stenosis
Cataracts
Entropion
Eversion of the cartilage of the third Eyelid
GM2 Gangliosidosis
Hemivertabra
Lymphedema
Lupoid Dermatosis
Progressive Retinal Atrophy
Cone Disease
Von Willebrand’s Disease
XX Sex reversal
Hip
Dysplasia
-Mutliple components affecting
tightness of hip joints
-May not become apparent until
much later in life
-Testing methods are primarily
subjective
--Two cleared parents are no
guarantee of clear offspring
--Multiple genes are involved
--Genetic testing will likely never
be possible
OFA Testing
-Prelims can be done early but
may not correlate with adult
scores
-certification not done until 2
years of age
-Completely subjective testing
-Films read by three boarded
radiologists
-Open submission system
leading to skewed results
-Useful tool but limited progress
on eliminating HD has been
achieved
•Results in Fail, Fair, Good
Excellent Ratings
PennHip
• -Certification can be done and is
accurate at 4 months. Correlates
with later scores.
• -Objective measurement of hip laxity
• Veterinarian must be certified
• Closed submission system
• Evidence that its use can decrease
incidence of HD
• Result is DI – Distraction Index
Pennhip Views
Compression Film
Distraction Film
Elbow dysplasia
•Developmental defect in
formation
of elbow joint
•One or more components
•Ununited Anconeal Process
•Fragmented Coronoid
Process
•Results in instability, pain,
lameness
and arthritis
•Usually apparent in young dog 68 months
•Screening by veterinarian
•OFA screening system
•Treated surgically
•Polygenic inheritence
Acral Mutilation
Syndrome
•May begin as early as
3-5 months of age
•Treatment is
symptomatic
•Believed to be
Autosomal recessive
•Dogs lose sensation in
feet
•Leads to chronic
licking, mutilation,
infection
•No testing currently
available
Aortic Stenosis
•Narrowing of Outflow tract
•Can result in failure
•Murmur detected at any
age
•Echocardiogram is
definitive
•Treatment is symptomatic
•Surgery in extreme cases
•Screening
•Auscultation
•Cardiac Certification
•Believed to be Autosomal
• Dominant
•No genetic test
Cataracts
•Opacity in lens
•Most are inherited but some are s
secondary to diseases
•Juvenile cataracts present early
•Others not apparent until later
•Screening by veterinarian
Or Ophthalmologist
Annual CERF testing since may
not show up until later in life
•Unknown mode of inheritence
•No genetic testing currently available
Entropion
•Inward rolling of eyelid usually lower
•One or Both eyes affected
•Results in corneal irritation, pain
discharge
• Usually Apparent early
•Screening by Veterinarian
•Corrected surgically
•Polygenic inheritance
•No Genetic testing
Eversion of Cartilage
of Third Eyelid
•Rolling in or out of
cartilage along
margin of third eyelid
•Results in chronic
irritation
•Screening by
veterinarian
•Surgically removed
•Unknown inheritance
•No genetic test
GM2 Gangliosidosis
• Storage disease of molecules which
lead to nerve damage
• Severe neurologic signs
• Apparent at 6-12 months of age
• Often have “Coarse” facial
appearance
• Screening by veterinarian
• Treatment is euthanasia
• Believed to be autosomal recessive
• No genetic test for GSHPs
Hemivertebra
•Abnormal development of one
or more vertebra
•May or may not cause neurologic
signs
•May be incidental finding
•No treatment unless compressing
spinal chord
•Screening by veterinarian
•Autosomal recessive
•No genetic testing
Lymphedema
•Abnormal or obstruction of lymph flow
•Results in severe swelling
•, usually hind legs first
•Treatment may or may not be needed
•Screening by veterinarian
•Autosomal Dominant
•Abnormal or obstruction of Lymph flow
•No genetic test
Lupoid Dermatosis
•Autoimmune disease
•Inflamed, crusty, itchy skin
•Usually begins at 6 months of age
•Begins on face and legs
•May spread to entire body
•Biopsy is definitive
•Variable response to treatment with
immunosuppressive drugs
Lupoid Dermatosis
•Funded research
ongoing at Univ Penn.
•Genetic Marker test
available
•May be unique to
GSHP
•Commercial testing
may be available in
near future
Progressive Retinal
Atrophy -PRA
•Progressive degeneration
of rods and cones
•Night blindness at age 2-5
•Progresses to complete
blindness
•Annual CERF testing
•No treatment available
•Genetic tests for some breeds
•Not GHSPs
•Autosomal recessive
Cone Degeneration CD
•Degeneration of Cones only
•Day blindess can begin as
early as 8-12 weeks
•Vision normal at night
•No treatment
•CERF testing
•Autosomal recessive
•Genetic Test Available!!
•Optigen
Cone Disease
Von Willebrand’s
Disease
•Lack of vWF factor in
blood
•Leads to prolonged
bleeding
•May or may not be
significant
•Can be managed if
known
•Screening as early as 6
weeks
•Autosomal recessive
with incomplete
expression
•Reported as factor
level
•Genetic Test for some
breeds, not GSHP
XX Sex Reversal
•Form of hermaphrodism
•Carries both ovaries and
testicle
•May have abnormal
external genitalia
•Screening by veterinarian
•Autosomal Recessive
NOW WHAT?
How do we put this knowledge to use to improve our breedin
Recommendations
• Develop stringent screening program
and
stick to it!
• Breed only cleared animals to
cleared animals
• Screen as early as feasible to
determine if dog should be retained
in program
• Don’t ever become discouraged.
Genetics is always a roll of the dice
we’re just beginning to understand
• Participate in breed studies when
possible
GSPCA
Recommendations
• Certify for Hip and Elbow
Dysplasia through OFA or
Pennhip
• Congenital Cardiac Clearance by
veterinary Cardiologist
• Annual CERF exams until age 6
then every two years
• Cone degeneration testing
through Optigen
Our Goal
Happy and Healthy German Shorthaired Pointe

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