Ultrasonography of the normal kidney in the cynomolgus monkey (Macaca fascicularis): morphologic and Doppler findings

The purpose of this study was to obtain sonographic measures of normal kidneys in cynomolgus monkeys (Macaca fascicularis). The kidneys of 27 healthy female cynomolgus monkeys were examined with two-dimensional, duplex and power Doppler under sedation or general anesthesia. Except for shape and sinus echogenicity, the kidneys of the cynomolgus monkey are morphologically similar to those of humans. Left kidney volume estimations (mean, 5.1 cm3) were significantly smaller (P<0.001) than those of the right (mean, 5.9 cm3), and both increased significantly with increasing body weight (P<0.05, r = 0.408). The mean resistive index (RI) of ketamine-sedated monkeys was 0.54, with an upper limit of 0.74 for the renal artery. The mean RI under general anesthesia was 0.65, with an upper limit of 0.77. Morphologic and Doppler ultrasound assessments of the kidneys can be consistently performed in the conscious cynomolgus monkey, and anesthesia can have hemodynamic effects that alter the Doppler arterial waveform.