Abstract

This study aims to evaluate the effect of intravenous contrast medium injection on kidney length using computed tomography (CT) in clinically healthy dogs. A retrospective analysis was conducted on CT examinations of the abdomen performed in 113 dogs (43 females, 70 males). Kidney lengths (K) were measured on precontrast and post contrast images. They were normalized using the length of the body of the second lumbar vertebra (L2), expressed as K/L2 ratio, and compared using paired t-tests. Precontrast normalized kidney length was 3.03±0.28 for the right kidney (PrRK) and 2.97±0.31 for the left kidney (PrLK). Post contrast normalized length was 3.06±0.30 for the right kidney (PcRK) and 3.0±0.31 for the left kidney (PcLK). On both precontrast and post contrast acquisitions, the right kidney was significantly longer than the left one (P <0.05) for a given dog. The mean increase in kidney length on post contrast images was 0.03 K/L2 for both kidneys compared to precontrast measurements. Males had significantly longer normalized kidney lengths than females in both precontrast and post contrast images (P <0.05). Intravenous contrast medium injection results in a slight but significant increase in kidney length in dogs on CT. This increase is consistent between the right and left kidneys. This study also found inherent anatomical variations, with males having longer normalized kidneys than females and the right kidney being longer than the left. These findings suggest that kidney length measurements can be reliably performed before or after intravenous contrast medium injection in clinical settings.