Transthoracic echocardiographic mensuration of two-dimensional left atrial to aorta ratios and left ventricular M-mode parameters in clinically normal adult Dachshunds

Abstract

Dachshunds are predisposed to myxomatous mitral valve disease (MMVD) with a polygenic mode of inheritance for mitral valve prolapse. Changes in left heart geometry have been previously observed in dogs with chronic volume overload secondary to mitral regurgitation) in MMVD, particularly left atrial enlargement. The primary objectives of this study were to estimate normal values for the left atrium to aorta (LA/Ao) ratio and establish normal prediction intervals for left ventricular motion-mode (M-mode) transthoracic echocardiographic measurements in clinically normal adult Dachshunds. The mean (standard deviation) for LA/Ao ratio measured in 40 clinically normal adult Dachshunds using the diameter, circumference and cross-sectional area standard two-dimensional methods via right parasternal short axis view were 1.40 (0.13), 2.19 (0.17) and 2.95 (0.48). The normal prediction intervals of the left ventricular measurements established via logarithmic transformation and linear regression in this study were found to have more narrow intervals than previous multi canine breed prediction intervals and were therefore more representative for clinically normal adult Dachshunds. The scaling exponents (b’) derived from this study ranged from 0.129 to 0.397 and did not absolutely conform to the presumed index of body length in the allometric equation, which is body weight raised to 1/3 power. The 2-D LA/Ao ratios and M-mode left ventricular prediction intervals established from this study may be used as reference values for Dachshunds.