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Conference abstract2007

A prospective cohort study of systolic ejection murmurs and the left ventricular outflow tract in boxer dogs during the growth period

Höglund, Katja; Häggström, Jens; Bussadori, Claudio; Kvart, Clarence

Abstract

There is a high prevalence of low intensity ejection murmurs in adult boxer dogs which may be related to abnormal development of the left ventricular outflow tract (LVOT). This has not previously been investigated in growing boxers. The aims of the current study were to compare the progression of heart murmurs, development of the LVOT and flow velocities in the great arteries during the first year of life in two groups of boxer puppies, those with and those without a low intensity ejection murmur at 7 weeks of age. Matched pairs of privately-owned boxers, one puppy with a low intensity ejection murmur and one without, were selected. None of the dogs had structural evidence of heart disease at inclusion. The dogs were studied prospectively with examinations at 7 weeks, 3, 4, 6, 9 and 12 months of age by cardiac auscultation, ECG and Doppler echocardiography. Variation in presence and intensity of heart murmurs was found in both groups, and there were no significant differences in LVOT dimensions between the groups. None of the dogs developed subvalvular aortic stenosis. Three dogs with grade II/VI murmurs at inclusion developed mild-moderate aortic insufficiency. There were no significant differences in aortic or pulmonic flow velocities between the groups at any of the examinations. In conclusion, the variability in presence and intensity of low intensity ejection murmurs is high during the first year of life in boxers. A subpopulation of dogs with grade II/VI murmurs appears to be at risk of abnormal development of the LVOT, as indicated by development of aortic insufficiency. The importance of a relatively smaller size of the LVOT in the genesis of low intensity ejection murmurs in boxers remains to be demonstrated

Conference

The European College of Veterinary Internal Medicine-Companion Animals