Ultrasonographically determined renal values and comparisons to serum biochemistry renal parameters in aged semi-captive cheetahs (Acinonyx jubatus)

Cheetahs in captivity have a high prevalence of chronic renal diseases. Abdominal diagnostic ultrasound is a useful diagnostic modality to evaluate the urinary tract and can give an immediate indication of renal status but lacks sensitivity and specificity for early renal changes in domestic carnivores. We ultrasographically evaluated the renal volumes, a variety of renal dimensions, interarcuate artery resistivity indices as well as aortic diameters and the length of the ventral aspect of the 6th lumbar vertebras in 27 aged semi-captive anesthetized cheetahs. A number of ultrasound ratios were determined to evaluate renal size and the dimensions and ratios were compared to serum creatinine and urea values as well as urine specific gravity. There were minimal differences for all values between left and right kidneys. Mean kidney length was 65 .4 mm (range 54.9-76.9) with left kidney length ratios to L6 length being 1.60 (range1.27-2.06) and to the aortic diameter 7.69 (range 4.54-10.72). Significant correlations between left renal length as well as length:L6 ratio to creatinine values were found ((r -0.66) and (r -0.60) respectively). The mean RI values of the different sedation/anesthetic protocols ranged from 0.46 -0.55. 4 – 0.66. Left renal length and L6 ventral vertebral body length as well as left kidney RI values should be measured in all cheetah abdominal ultrasound examinations. These measurements, together with serum creatinine, urea and urine specific gravity values may be relatively sensitive indicators of early renal pathology in the absence of gross ultrasonographic changes.