Quantitative Ultrasound of Kidneys, Liver, and Spleen: a Comparison Between Mules and Horses

An ultrasonographic evaluation of the renal morphology is subjective in veterinary science. The echogenicity and echotexture are compared among the cortex, medulla, liver, and spleen. The purpose of this study was to quantify the renal echogenicity and echotexture of healthy adult horses and mules. An ultrasonographic examination was performed on 12 horses and 12 mules to obtain bidimensional images of the renal cortex, renal medulla, liver, and spleen. These images were analyzed using a gray-level histogram to obtain the quantitative values of echogenicity, echotexture, and the proportions of each region. Difference between the kidneys of mules and horses was observed. The renal cortex was less echoic (6.59 ± 1.69 less in mules; 3.04 ± 1.03 less in horses) and more homogeneous (0.17 ± 0.24 more in mules; 0.47 ± 0.22 more in horses) than the spleen but more hypoechoic (1.46 ± 0.37 more in mules; 1.05 ± 1.07 more in horses) and homogeneous (0.81 ± 0.11 more in mules; 0.85 ± 0.26 more in horses) than the liver. In comparing the renal cortex to the medulla, it was observed that the renal cortex is more echoic (up to 3.49 ± 1.59 more in mules; 2.07 ± 0.21 more in horses) and heterogeneous (up to 0.45 ± 0.23 more in mules; 0.63 ± 0.09 more in horses). The most important difference between mules and horses was a more hypoechoic and homogeneous renal medulla in mules, indicating a higher water content of the renal medulla in mules than in horses.