Repeatability of standard transthoracic echocardiographic measurements in horses

Objectives To assess the repeatability of commonly employed transthoracic echocardiographic measurements in standing horses. Design Thirteen healthy 3- to 4-year-old fit Standardbred geldings with a mean weight of 411 (SEM +/- 10) kg were studied. The horses' environment, feeding and management regimens were standardised. All measurements were performed by the same investigator at the same time every day for three consecutive days. Procedures Standard transthoracic measurements were made on all horses. Each measurement was performed over three consecutive cardiac cycles on 1 day and all measurements were performed over 3 consecutive days. Summary statistics of each day were then compared using an analysis of variance with times as a repeated measures factor. Statistical significance was set at P < 0.05. Results Many of the standard echocardiographic measurements used to derive quantitative and functional information about the equine heart have a low intra-observer variability. Conclusions Standard transthoracic echocardiographic measurements have a low enough intra-observer variability to warrant their use for clinical and experimental studies.