Use of computed tomography for measurement of kidneys in dogs without renal disease.

OBJECTIVE To determine the size of the left and right kidneys by use of CT in dogs of various breeds without evidence of renal disease. DESIGN Retrospective, observational study. ANIMALS 21 client-owned dogs. PROCEDURES Renal length, diameter of the abdominal aorta, and length of the L2 vertebral body were measured independently on multiplanar reformatted non-contrast-enhanced CT images by 3 observers at 3 time points. Intraobserver and interobserver agreement for renal length were determined. Associations of renal length with body weight, aorta diameter, and L2 vertebral body length were assessed by calculation of Pearson correlation coefficients and 95% confidence intervals. Renal measurements were normalized to patient size by calculating renal length-to-aorta diameter and renal length-to-L2 vertebral body length ratios for comparison with previously published radiographic and ultrasonographic measurements. RESULTS All kidneys were identified and measured on CT images by all observers. Intraobserver and interobserver agreement were excellent. Body weight, aorta diameter, and length of the L2 vertebral body were significantly correlated with renal length. Renal length-to-aorta diameter and renal length-to-L2 vertebral body length ratios (7.4 and 2.7, respectively) fell within the ranges of previously published values for these measurements. CONCLUSIONS AND CLINICAL RELEVANCE As CT becomes more widely available in general practice, knowledge of typical renal measurements and anatomic ratios obtained with this modality in dogs may be useful. A prospective study with a larger population of dogs, ideally including formulation of a reference range, is needed.