Discussion

Aims: To evaluate a novel translumbar (TL) ultrasonographic method for assessment of renal dimensions, establish a normal reference range and compare reliability of renal dimensions obtained using the TL projection with a conventional transabdominal (TA) projection and measurements obtained at post mortem. Methods: Six Thoroughbred or Thoroughbred cross horses, weighing 513 plusminus 49kg, were examined prior to slaughter. Both kidneys were imaged in short and long axis using the TL and TA projections. Both cranial and caudal poles of the right kidney were assessed. A minimum of 12 ultrasonographic cineloops were obtained from both kidneys and stored for subsequent analysis. The kidney length, width and depth were determined, as were the thickness of the cortex, medulla and pelvis. The measurements were repeated in matched cadavers. All measurements were undertaken by 2 observers to assess reproducibility and measured on 3 separate occasions by one observer to evaluate repeatability. Measurements were compared using student's t test, ANOVA and post hoc Bonferroni and coefficient of variation and reliability was assessed using repeated measures ANOVA and intra-class correlation coefficients (ICCs). Results: Both kidneys were consistently identified by both methods in the 15 - 17th intercostal spaces (ICS) and paralumbar fossa with maximal dimensions obtained for the left kidney in the 16th ICS and for the right kidney in the 15th ICS. Image quality was good to excellent for both techniques. There was no difference between dimensions obtained by TA or TL projections and good correlation between ultrasound dimensions and post mortem measurements existed (Table 1; ICC>0.8). Excellent repeatability and reproducibility (ICC>0.80) was obtained for all measurements. Reliability was better for larger structures. Conclusions and practical significance: The TL technique is easily performed and produces reliable dimensions that may assist with the diagnosis of renal disease in horses. Acknowledgements: Thanks to staff at Potters Abattoir, Somerset for their assistance with the study.