Mitral annular plane systolic excursion (MAPSE) is an M-mode index of left ventricular longitudinal systolic motion. In dogs, interpretation of raw MAPSE is affected by wide body size variation; and the independent effect of age after body weight adjustment has not been quantified. This study aimed to develop a body weight- and age-adjusted reference model for septal MAPSE and derive normalized indices. This two-center retrospective study included 180 client-owned healthy dogs examined between November 2016 and December 2023. Inclusion criteria included the absence of structural cardiac abnormalities, sinus rhythm, systolic blood pressure <140mmHg, and no clinically relevant thoracic radiographic, hematologic, or biochemical abnormalities. Septal MAPSE was measured by M-mode echocardiography from the apical four-chamber view and averaged over three cycles. Multiple linear regression modeled log₁₀(MAPSE), using log₁₀(body weight) and age. Heart rate and sex/neuter status were assessed as additional covariates, and study center was assessed for systematic center-related differences. Model-based Z-scores and percentage of predicted MAPSE values were calculated. The final model was log₁₀(MAPSE)=0.6279+0.3243× log₁₀(BW)−0.008767×age, explaining 70.2% of variation in log₁₀(MAPSE). Body weight and age were significant predictors (P<0.0001). Predicted MAPSE scaled allometrically with body weight and decreased by 2.0% per year. Z-scores and percentage of predicted MAPSE showed no residual association with body weight or age. Septal MAPSE in healthy dogs is body weight- and age-dependent. This model provides body weight- and age-adjusted expected values for interpreting septal MAPSE within the range represented by this cohort.

To Cite This Article: Zheng ZJ, Chang MH, Shia WY, Lee WM and Lai CH, 2026. Body weight- and age-adjusted reference model for septal mitral annular plane systolic excursion in healthy dogs. Pak Vet J, 2026, 46(10): 2628-2636. http://dx.doi.org/10.29261/pakvetj/2026.252