Familial Subvalvular Aortic Stenosis in the Rottweiler

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Familial Subvalvular Aortic Stenosis in the
Rottweiler

• Joshua A Stern, DVM jstern_at_vetmed.wsu.edu
• Veterinary Cardiac Genetics Laboratory
• Washington State University College of Veterinary
  Medicine

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Outline

• Overview of SAS
• Diagnosis Breeding Recommendations
• Outcomes
• Pedigree Analysis
• Population Genetics

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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
• Most common in large breed dogs
• Familial link demonstrated in Newfoundlands

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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

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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
• Echocardiography elevated aortic velocities
• Auscultation not specific for SAS
• Angiography presence of subvalvular stenosis

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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

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Aortic Velocities

• ARCH Recommendations
• lt1.9 m/s normal (clear for breeding)
• 1.9-2.4 m/s equivocal (breeding assumes a certain
  risk level)
• gt 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

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Prognosis

• Based on echocardiographic analysis of severity
  as Mild
• Typically have normal lifespan
• Increased risk of bacterial endocarditis
• May produce puppies with disease more severe than
  their own

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Prognosis

• Based on echocardiographic analysis of severity
  as Moderate
• Increased risk of sudden death, heart failure
• May live normal lifespan
• Increased risk of bacterial endocarditis

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Prognosis

• Based on echocardiographic analysis of severity
  as Severe
• High risk of sudden death, heart failure
• Few live normal lifespan (19-45 months)
• Increased risk of bacterial endocarditis

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Breeding Considerations

• SAS appears familial in Rottweiler
• Removing dogs from breeding pool should be done
  with caution
• Small gene pool
• Equivocal category is still uncertain
• Aortic velocity is not a static measure

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Pedigree Analysis
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

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Our Study Continued

• Focus search in regions of interest for a
  mutation
• Identification of a mutation or mutations that
  cause SAS (a potential screening tool)
• Participation is confidential

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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

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Questions
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Acknowledgements

• Veterinary Cardiac Genetics Laboratory
• American Kennel Club Health Foundation
• Rottweiler Club of America