[Ultrasonography in neonatal foals: Depiction and measurement of the kidneys].

OBJECTIVE: Aim of the study was to describe the echotexture and dimensions of the kidneys including the renal pelvis in neonatal foals using transabdominal sonography. MATERIAL AND METHODS: In the course of a preliminary examination, sonographic examinations of the kidneys of 10 dead newborn foals were performed in order to determine their localization, measurement parameters, and echotexture. In subsequent necropsies, the kidneys were measured and the obtained values were compared with the sonographic measurements. A high level of agreement between the both measurement values could be demonstrated. In the main examination, 57 1- to 14-day old foals of different breeds were examined. The intercostal spaces and the fossa paralumbalis of both body halves were scanned in longitudinal direction and the topography and echotexture of the kidneys were evaluated using a standardized sonographic examination procedure. The length and width of the organ as well as the extent of the renal pelvis were measured during the same procedure. The obtained measurement values were analyzed comparatively under consideration of different breeds. RESULTS: The renal capsule was identified sonographically by the depiction of a fine hyperechogenic line. The renal cortex itself proved to be echogenic in the ultrasonographic image and the renal medulla hypoechogenic. The renal pelvis exhibited a hyperechogenic sound image. The mean length and width of the left kidney amounted to 7.1 +/- 1.4 cm and 4.2 +/- 0.7 cm, respectively. The right kidney measured 6.7 +/- 1.4 cm and 3.9 +/- 0.7 cm in mean length and width. The measurement of the left renal pelvis resulted in mean values of 1.3 +/- 0.7 cm in length and 0.7 +/- 0.4 cm in in width. Mean length and width of the right renal pelvis amounted to 1.3 +/- 0.6 cm and 0.6 +/- 0.4 cm, respectively. The renal pelvis displayed an anechogenic lumen on the left and right sides in 24.6 % and 64.3 % of the foals, respectively. The comparison of the measurement values under consideration of different breeds showed that body weight of the equine neonates did not exhibit a correlation with kidney size. CONCLUSION AND CLINICAL RELEVANCE: Transabdominal sonography is a reliable diagnostic tool for the evaluation of kidneys in neonatal foals. The description of physiological renal echotexture and dimensions serves to identify pathological conditions.