Transabdominal ultrasonographic measurement of caudal vena cava to aorta derived ratios in clinically healthy neonatal foals

Abstract

Background

Ultrasonographic measurement of the vena cava and aorta (Ao) diameters and their ratios have been suggested to be a reliable way of quantifying hypovolemia.

Objective

To evaluate the feasibility and reliability of an ultrasonographic technique for measurement of Ao and caudal vena cava (CVC) and derived ratios using three different acoustic windows in a population of healthy neonatal foals. Correlation between Ao and CVC measurements and ratios and foals' age or bodyweight were also investigated.

Methods

In 14 healthy foals aged less than 7 days, the diameters of the Ao and of the CVC in long and short axis were measured by two observers from images obtained using three different ultrasonographic imaging planes (left dorsal, left ventral and right views). The Ao and CVC cross‐sectional area and the CVC/Ao diameter and area ratios were calculated. Image quality was subjectively assessed. Intraobserver and interobserver reliabilities for image quality scores and measurements were evaluated between the two observers. Simple linear regression models were used to identify correlations between the CVC/Ao measurements and ratios and the age and bodyweight of the foals.

Results

The left ventral view showed the highest reliability. A correlation between bodyweight and the short axis measurement of the CVC was found ( R ² = 0.385; p = 0.018). Age was positively correlated with the long axis of measurement of the CVC ( R ² = 0.426; p = 0.011) and CVC/Ao diameter ratio ( R ² = 0.625; p = 0.001).

Conclusions

The left ventral view allows the Ao and CVC cross sections to be easily visualized and measured in neonatal foals in right lateral recumbency.

Abstract

The present study evaluated the feasibility and reliability of an ultrasonographic technique for measurement of Ao and CVC and derived ratios using three different acoustic windows in a population of healthy neonatal foals. A left ventral view of the abdomen allowed for rapid imaging and measurement of the cross‐sectional diameter of both the aorta and the CVC in neonate foals in lateral recumbency, and might be a promising method to quantitatively assess the degree of hypovolemia.