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5/26/2010
Familial Subvalvular Aortic
Stenosis in the Rottweiler
Joshua A Stern, DVM [email protected]
Veterinary Cardiac Genetics Laboratory
Washington State University College of Veterinary Medicine
Outline
• Overview of SAS
• Diagnosis & Breeding
Recommendations
• Outcomes
• Pedigree Analysis
• Population Genetics
SAS in Rottweilers
• Devastating disease
• Mild forms of disease can go
unrecognized
• Rottweilers over represented
• Appears familial
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Background:
Subvalvular Aortic Stenosis
• Commonly reported congenital heart disease
• Characterized by aortic subvalvular ridge
Characterized by aortic subvalvular ridge
• Most common in large breed dogs
• Familial link demonstrated in Newfoundlands
Physiologic Consequences of SAS
• Aortic stenosis increases
pressure in the left side of
the heart
• Left ventricular heart
muscle thickens in
response to pressure
• Aorta can dilate after the
stenosis
Consequences of SAS Continued
• Aortic valve may leak
• Thick heart muscle does not oxygenate
well
• The thick muscle with less oxygen can
lead to rhythm disturbances
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Diagnosis:
• Gold Standard – Necropsy demonstration of subvalvular ridge, ring, band or nodules
• Diagnostic tests Di
i
– Echocardiography : elevated aortic velocities – Auscultation: not specific for SAS
– Angiography: presence of subvalvular stenosis
Auscultation Screening
• Ausculation screening is a good first step
– Dogs that pass are unlikely to have SAS
– Dogs that fail may or may not have SAS
– Echocardiography can help differentiate dogs
with functional murmurs from those with SAS
Aortic Velocities
• ARCH Recommendations
– <1.9 m/s normal (clear for breeding)
– 1.9-2.4 m/s equivocal (breeding assumes a
certain risk level)
– > 2.4 affected (breeding not recommended)
*ARCH = ACVIM Registry of Cardiac Health
(guidelines established by veterinary cardiologists)
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Prognosis for dogs with SAS
• Highly variable
– No clinical
consequences
– Sudden Death
– Congestive Heart
Failure
– Potential to pass on
more severe form to
offspring
Prognosis
• Based on echocardiographic analysis of
severity as Mild
– Typically
T i ll h
have normall lif
lifespan
– Increased risk of bacterial endocarditis
– May produce puppies with disease more
severe than their own
Prognosis
• Based on echocardiographic analysis of
severity as Moderate
– Increased
I
d risk
i k off sudden
dd d
death,
th h
heartt ffailure
il
– May live normal lifespan
– Increased risk of bacterial endocarditis
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Prognosis
• Based on echocardiographic analysis of
severity as Severe
– High
Hi h risk
i k off sudden
dd d
death,
th h
heartt ffailure
il
– Few live normal lifespan (19-45 months)
– Increased risk of bacterial endocarditis
Breeding Considerations
• SAS appears familial
in Rottweiler
• Removing dogs from
b di pooll should
breeding
h ld
be done with caution
– Small gene pool
– Equivocal category is
still uncertain
– Aortic velocity is not a
static measure
Pedigree Analysis
KEY
F
M
Normal
Affected
Unknown
Not enough information at this time but appears to skip generations
*consistent with a recessive trait*
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Our Study
• Enroll affected and normal Rottweilers
• Use SNParray to analyze entire genome
• Identify regions that are different between
normal and affected
Our Study Continued
• Focus search in regions of interest for a
mutation
• Id
Identification
tifi ti off a mutation
t ti or mutations
t ti
that cause SAS (a potential screening tool)
• Participation is confidential
We Are Still Enrolling
• Normal or affected Rottweilers of variable
lineage
• Echocardiography results from cardiologist
• 3 generation pedigree
• Blood sample (3ccs purple top tube)
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Conclusion
•
•
•
•
SAS is a life threatening disease
Appears to be inherited in the Rottweiler
Pattern of inheritance is still unclear
Screening is important in reducing
prevalence
• Genetic studies are underway to identify
possible mutations
Questions
Acknowledgements
• Veterinary Cardiac Genetics Laboratory
• American Kennel Club Health Foundation
• Rottweiler Club of America
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