Ultrasound features of kidneys in the rabbit Oryctolagus cuniculus

Purpose: To determine the normal sonographic features of rabbit kidneys with regard to their use in diagnostic imaging of renal lesions in this species.Materials: Twelve sexually mature clinically healthy New Zealand White rabbits weighing 2.8 kg to 3.2 kg were examined after anaesthesia.Methods: A diagnostic ultrasound system with microconvex multifrequency 6.5 MHz probe was used.The animals were positioned in dorsal recumbency.The transabdominal paravertebral imaging approach was used.Longitudinal and transverse scans of the kidneys were obtained.Six rabbits were sacrificed, their kidneys removed and studied in isotonic liquid medium.Results: The shape of kidneys was elliptical.The fibrous capsule was visualized as a straight hyperechoic band.The fatty capsule was hyperechoic and with irregular borders.The cortex exhibited a heterogeneous echogenicity.The acoustic density of the cortex was lower than that of the liver.The echoicity of the medulla was lower as compared to the cortex and the structures of the kidney pelvis.The latter appeared as a centrally located hyperechoic structure.The post mortem examination showed that kidneys were oval and hyperechoic.The kidney pelvis was seen as a centrally located longitudinal finding, and the renal hilum -as a centrally located hyperechoic finding.Conclusions: The transabdominal paravertebral approach was a good method for visualization of rabbit kidneys.The dorsal recumbency of the subjects allowed the visualization.The in vivo results corresponded to those from the post mortem study.The rabbit kidney was oval in shape.The hypoechoic peripheral zone is occupied by the cortex and the medulla, while the hyperechoic central zone -by the kidney pelvis.The cortex was less echoic than the liver parenchyma.The kidney pelvic cavity had a lower acoustic density than its walls, due to the presence of peripelvic adipose tissue.The present results could be used in the interpretation of normal and pathological renal findings in the rabbit.