Allometric Scaling of M-Mode Cardiac Measurements in Normal Adult Dogs

Abstract

Indices for M-mode measurements in dogs usually have been based on the assumption that a linear relationship exists between these measurements and body weight (BW) or body surface area (BSA). The relationships between the geometry of 3-dimensional objects do not support this assumption. The purposes of this study were to retrospectively examine M-mode data from a large number of dogs of varying sizes and breeds that were examined by a large number of ultrasonographers, to use the allometric equation to determine the appropriate BW exponent required to predict these cardiac dimensions, and to determine normal mean values and prediction intervals for common M-mode variables. Linear regression analyses of data from 494 dogs (2.2-95 kg) revealed a good correlation between M-mode measurements and BW after logarithmic transformation of the data (r 2 .55-.88). Most variables were most closely related to an index of body length, BW 1/3 , although the exponent that best predicted diastolic and systolic left ventricular wall thicknesses was closer to 0.25. No variable indexed well to BW or BSA. With these data, appropriate mean values and prediction intervals were calculated for normal dogs, allowing veterinarians to correctly and appropriately index M-mode values. The equations developed from this study appear to be applicable to adult dogs of most breeds.

A prospective, randomized, double‐blind, placebo‐controlled pilot study of sacubitril/valsartan (Entresto) in dogs with cardiomegaly secondary to myxomatous mitral valve disease

“…Each patient had to show all of the following echocardiographic and thoracic radiographic criteria to be classified in Stage B2: classic myxomatous lesions of the mitral valve apparatus, mitral regurgitation (MR) on color Doppler interrogation, left atrial enlargement based on a left atrial‐to‐aortic root ratio (LA : Ao on the right parasternal short axis view) ≥ 1.6,26 left ventricular enlargement based on an internal diameter in diastole indexed to body weight (iLVIDd)27 ≥ 1.7, and radiographic evidence of cardiomegaly (vertebral heart score [VHS]28 > 10.5). Each dog was required to be on pimobendan (0.5‐0.6 mg/kg/day PO in divided doses; Boehringer Ingelheim, Ingelheim am Rhein, Germany) for at least 7 days before baseline sampling (day 0) as well as to continue pimobendan until the completion of the study 29…”

“…M‐mode echocardiography was used to obtain the left ventricular internal diameter at end‐diastole (LVIDd) and the left ventricular internal diameter at end‐systole (LVIDs) using the right‐parasternal short‐axis view 33. Left ventricular internal diameter at end‐diastole indexed to body weight was calculated using the formula (iLVIDd) = LVIDd (cm)/[BW (kg)] 0.294 and LVIDs indexed to body weight (iLVIDs) was calculated with the formula (iLVIDs) = LVIDs (cm)/[BW (kg)] 0.315 27. The tricuspid valve was assessed for regurgitation (TR) with color Doppler interrogation, and if present, the instantaneous peak systolic tricuspid regurgitant velocity was measured using continuous‐wave Doppler interrogation.…”

Vitamin D Status in Different Stages of Disease Severity in Dogs with Chronic Valvular Heart Disease

“…Left ventricular end‐diastolic diameter was normalized for body weight (LVEDDN) using the following formula: left ventricular end‐diastolic diameter/(body weight [kg]) 0.294 . Left ventricular end‐systolic diameter was normalized for body weight (LVESDN) using the following formula: left ventricular end‐systolic diameter/(body weight [kg]) 0.315 14. Left atrial‐to‐aortic root ratio (LA/Ao) was obtained from the 2‐D right parasternal short‐axis view 15.…”

“…Stage B1 included dogs without clinical signs of CVHD and echocardiographic evidence of cardiomegaly (ie, LA/Ao < 1.6 and LVEDDN < 1.85) 14, 15, 17, 18. In the present study, Stage B1 dogs were regarded as hospital controls (control group dogs) because: (1) it would be difficult to recruit demographically matched healthy controls for Stage B2 to D dogs considering their demographics and the prevalence of CVHD, and (2) Stage B1 dogs were deemed healthy except for having hemodynamically inconsequential mitral regurgitation and were expected to be relatively well‐matched for demographics with Stage B2 to D dogs.…”

Effect of prespecified therapy escalation on plasma NT‐proBNP concentrations in dogs with stable congestive heart failure due to myxomatous mitral valve disease

“…Left ventricular internal dimension in systole was normalized for body weight (LVIDSN) using the formula: LVIDs/(body weight [kg]) 0.315 . Left ventricular internal dimension in diastole was normalized for body weight (LVIDDN) using the formula: LVIDd/(body weight [kg]) 0.294 18. Dogs were grouped based on whether their NT‐proBNP concentration at visit 0 was < or ≥1500 pmol/L.…”