Feasibility of Baseline Cardiac Investigation in Awake Elephants (Elephas maximus) Using Transthoracic Echocardiography: the BIG HEART study

Abstract

IntroductionCardiovascular diseases are relatively common in elephants, but most cases are diagnosed only postmortem. Transthoracic echocardiography (TTE) is widely used in domestic and captive animals, although its application in elephants has not yet been established. The aim of this pilot study was to determine the feasibility of performing TTE in Asian elephants (Elephas maximus), to develop a standardized procedure to optimize image quality, and to assess measurement variability. Materials and MethodsPreliminary trials were conducted in ten elephants, including seven free-ranging animals in Cambodia and three captive elephants in France. These led to a standardized TTE protocol based on cooperative training and positive reinforcement. Key refinements included the exclusive use of a left parasternal approach, soaking the thoracic skin with lukewarm water before application of coupling gel, and extension of the left forelimb over a training ball to optimize access to the acoustic window. Each examination included two LV views: a long-axis view for M-mode measurements and a short-axis view for two-dimensional (2D) analysis. A total of 72 examinations were performed on 4 days on three elephants, with offline assessment of eight 2D and M-mode variables, including two indices of LV function (shortening fraction and fractional area change). A general linear model was used to determine within-day and between-day coefficients of variation. ResultsAll examinations were successfully completed without anesthesia or restraint. Within-day and between-day variability were low for all parameters (coefficients of variation <10%), while interindividual variability was higher (5%-19.6%). DiscussionLV dimensions and systolic function can be assessed in awake Asian elephants with excellent repeatability and reproducibility. ConclusionsThe validated TTE procedure developed here enables longitudinal cardiac monitoring in captive Asian elephants without anesthesia, providing a unique opportunity for the antemortem diagnosis of left-sided heart disease and facilitating future comparative and conservation studies in this endangered species.