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Systolic ejection murmurs and the left ventricular outflow tract in boxer dogs

physiology and clinical evaluation

Höglund, Katja (2007). Systolic ejection murmurs and the left ventricular outflow tract in boxer dogs. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2007:24
ISBN 978-91-576-7323-7
[Doctoral thesis]

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Turbulence of various genesis in the left ventricular outflow tract (LVOT) causes systolic ejection murmurs. The prevalence of murmurs in adult boxer dogs is 50-80%, the majority of which are of low intensity. Some of the murmurs are caused by aortic stenosis (AS), while the origin of the others is unclear. The aim of this thesis was to study the physiology and clinical evaluation of systolic ejection murmurs and their relation to the development of the LVOT in boxers with and without AS. Growing and adult boxer dogs were examined by the standard methods cardiac auscultation, ECG, phonocardiography and echocardiography. Additionally, the complementary methods time-frequency and complexity analyses of heart murmurs and contrast echocardiography were evaluated. Studies on inter-observer variation in cardiac auscultation proved the importance of experience in detection and grading of low intensity ejection murmurs. Excitement of the dogs by exercise or noise stimulation (barking dog and squeaky toy) caused higher murmur grades, longer murmur duration and increased aortic flow velocities. No differences were found between diameters measured at different levels of the LVOT in growing boxers. Contrast echocardiography enhanced Doppler signals, but did not allow evaluation of myocardial blood flow. Using time-frequency analysis, duration of murmur frequency >200 Hz proved useful for differentiation between dogs with mild AS and dogs without. Combining assessment of murmur duration >200 Hz and complexity analysis using the correlation dimension (T2), a sensitivity of 94% and a specificity of 82% for differentiation between dogs with and without AS was achieved. The variability in presence and intensity of low intensity murmurs during growth was high. None of the young dogs developed AS, whereas 3 out of 16 individuals developed mild-moderate aortic insufficiency. Aortic or pulmonic flow velocities did not differ significantly between growing dogs with or without low intensity murmurs. In conclusion, the variability in presence and intensity of low intensity ejection murmurs in boxers is high during growth with no obvious progression. Both in young and adult boxers the murmur grade increased during excitement, which may be due to rapid flow in a comparatively small LVOT that has been suggested for the boxer breed. Experience is important in cardiac auscultation of low intensity murmurs. Therefore, assessment of murmur duration > 200 Hz combined with T2 analysis may be a useful complementary method for diagnosis of cardiovascular function in dogs.

Authors/Creators:Höglund, Katja
Title:Systolic ejection murmurs and the left ventricular outflow tract in boxer dogs
Subtitle:physiology and clinical evaluation
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :May 2007
Number of Pages:53
ALLI. K. Höglund, A. French, J. Dukes-McEwan, J. Häggström, P. Smith, B. Corcoran, C. Kvart. Low intensity heart murmurs in boxer dogs: Inter-observer variation and effects of stress testing. Journal of Small Animal Practice 2004; 45: 178-85 II. K. Höglund, C. Bussadori, O. Domenech, J. Häggström, D. Pradelli, C. Kvart. Contrast echocardiography in Boxer dogs with and without aortic stenosis. Journal of Veterinary Cardiology (In press) III. K. Höglund, C. Ahlstrom, J. Häggström, P. Ask, P. Hult, C. Kvart. Time-frequency and complexity analyses for differentiation of physiologic murmurs from heart murmurs caused by aortic stenosis in Boxers. American Journal of Veterinary Research (In press) IV. K. Höglund, J. Häggström, C. Bussadori, C. Kvart. A prospective cohort study of systolic ejection murmurs and the left ventricular outflow tract during the growth period in boxer dogs. (Submitted)
Place of Publication: Uppsala
Publisher:Dept of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences
Associated Programs and Other Stakeholders:SLU - Research Areas for the Future > Future Animal Health and Welfare (until Jan 2017)
ISBN for printed version:978-91-576-7323-7
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:dogs, arteries, disorders, cardiovascular diseases, echography, heart, diagnosis
Keywords:systolic ejection murmur, aortic stenosis (AS), aortic insufficiency (AI), left ventricular outflow tract (LVOT), boxer dog, auscultation, phonocardiography, echocardiography, murmur analysis
Permanent URL:
ID Code:1462
Faculty:VH - Faculty of Veterinary Medicine and Animal Science
Department:(VH) > Dept. of Anatomy, Physiology and Biochemistry
Deposited By: Katja Höglund
Deposited On:22 May 2007 00:00
Metadata Last Modified:02 Dec 2014 10:12

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