| Summary: | The basic hypothesis tested in this study was that dogs with dilated cardiomyopathy have abnormal ventricular function, and that this can be detected noninvasively using M-mode, two-dimensional (2D), and Doppler echocardiography, and also by measuring myocardial ultrasonic integrated backscatter. An additional hypothesis was that different breeds of dogs affected with DCM have a different clinical course, and that differences in ventricular function between these breeds can be detected by echocardiography or integrated backscatter measurements that might account for the different prognosis. The aims of this study therefore were (1) to identify echocardiographic variables that distinguished normal dogs from dogs with DCM; (2) to identify differences in ventricular function using echocardiography between Dobermanns and English cocker spaniels with DCM; and (3) to measure ultrasonic integrated backscatter in normal dogs and in Dobermanns and Cocker spaniels with DCM. In this group of Dobermanns, median survival time was 98 days (range 16-508 days), whereas median survival in the cocker spaniels was 530 days (range 51 to >1428 days), with 6/11 still alive at the time of writing (p < 0.002). All the measured M-mode variables differed significantly between the normal dogs and the dogs with DCM. Compared with the Dobermanns, the cocker spaniels had significantly increased LV free wall thickening and increased LV diastolic diameter when indexed to body surface area. All the 2D echocardiographic variables were significantly different between the normal dogs and dogs with DCM when corrected for body size. There were no significant differences between Dobermanns and cocker spaniels. Significant differences were found between normal and DCM dogs in some but not all of the Doppler echocardiographic variables. Cocker spaniels had higher mitral A wave velocities than the normal dogs, and decreased mitral E/A ratios than both the other groups. Dobermanns had shorter isovolumic relaxation times than the other groups.
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