Use of radiographs and computed tomography for measurement of kidney size in healthy chinchillas (Chinchilla lanigera)

BackgroundChinchillas, being small mammals, are subject to many of the urinary disorders that affect other companion animals. In cats and dogs, relationships between renal length and the presence of renal pathology have been well documented through the use of diagnostic imaging. Radiography and computed tomography (CT) are two commonly utilized diagnostic imaging modalities for assessing renal pathology. Presently, there are no published data on chinchilla kidney size and appearance using radiography or CT. This study aimed to determine healthy adult chinchilla renal size and correlate renal size to L2 body length and aortic diameter by use of radiography and CT.MethodsTwenty-eight healthy adult chinchillas with no clinical evidence of renal disease were placed under sedation for acquisition of radiographs and CT imaging. Both kidneys were measured on the radiographic views (right lateral, left lateral and ventrodorsal), when identifiable. Renal length, L2 body length and abdominal aortic diameter were measured on CT multiplanar reformatted images in specified planes and windows.ResultsIn 25% (7/28) of chinchillas, the renal length of either kidney could not be obtained on any of the three radiographic views due to superimposition of fluid and ingesta within the alimentary tract. Both the right and left kidney were identified on CT images in 100% of chinchillas (28/28). The left renal and right renal 95% confidence intervals from the dorsal plane CT images were 2.26 – 2.33 cm and 2.31 – 2.39 cm, respectively. No correlation was found between kidney length, L2 body length and diameter of the abdominal aorta on CT images.ConclusionsBased on dorsal plane CT imaging, normal chinchilla renal length is proposed to be between 2.25–2.4 cm.Clinical RelevanceRadiographic evaluation of chinchilla renal length is greatly limited due to their large fluid- and ingesta-filled colon and cecum, as is typical of animals that are hindgut fermenters. Through establishment of a normal CT reference interval for renal length and the ever-increasing clinical utility of CT, clinicians can better evaluate chinchilla renal length and identify alterations that may indicate pathologic processes.