Comparison of two-dimensional echocardiographic measurements of the left atrium in healthy dogs.

The aim of the study was to establish normal echocardiographic values of the left atrium just above the mitral annulus (LAama) in healthy dogs. In the first part of the study 20 dogs of various breeds were examined. The diameter of the left atrium just above the mitral annulus (LAama) was compared to the linear (left to right) dimension of the left atrium (LAr-l) as published earlier. There was a linear relationship between LAr-l and the body weight (LAr-l = 0.5061 BW (kg) + 22.206; R2 = 0.81), but the proportion of LAr-l/LAama was independent of the body weight (LAr-l/LAama = 0.0004 BW (kg) + 1.0833; R2 = 0.01). In the second part of the study the left atrial diameter just above the mitral annulus (LAama) was measured in 121 dogs of various breeds. There was a positive linear relationship (R2 = 0.697; p < 0.001) between body weight and LAama (LAama = 0.54 BW (kg) + 18.502+/-4.76), but there were no significant correlations between the age of animals and LAama (p = 0.45) as well as between the gender of animals and LAama (p = 0.78). Two-dimensional echocardiographic (2DE) determination of LAama as described in the present study can be recommended for use in those dogs where measurement of LAr-l encounters technical difficulties. In these cases LAr-l can be calculated from LAama using the formula LAr-l/LAama = 0.0004 BW (kg) + 1.0833, worked out in the first experiment.