Establishment of Reference Intervals for Caudal Vena Cava-to-Aorta Ratio Measured Ultrasonographically in Healthy Nonsedated Dogs.

The ultrasonographic assessment of the caudal vena cava-to-aorta ratio (CVC:Ao) appears to be a promising method for early recognition of alterations of intravascular volume status in veterinary medicine. The primary objective of this study was to establish the reference intervals of the CVC:Ao ratio with ultrasound in nonsedated healthy dogs. Secondary objectives were to determine the influence of the respiratory cycle and to evaluate correlations between ultrasonographic measurements, signalment and physical exam findings.