Computed tomographic assessment of abdominal aortic diameter is not associated with systemic hypertension in dogs: A preliminary study.

BACKGROUND

Systemic hypertension in dogs requires timely diagnosis to prevent damage to the target organ. Although ultrasonographic assessment of the aorta-to-caudal vena cava (Ao/CVC) ratio has been proposed as a noninvasive indicator of elevated blood pressure, no studies have explored whether computed tomography (CT) can serve the same purpose. CT offers objective vascular measurements and may overcome some limitations of ultrasonography.

AIM: This study aimed to determine whether CT-derived vascular ratios, specifically the Ao/CVC and a novel aorta-to-first lumbar vertebra (Ao/L1) ratio, differ between hypertensive and normotensive dogs. The influence of anesthetic status and measurement site on these ratios was also examined.

METHODS

In this retrospective study, 32 dogs that underwent same-day CT and Doppler Blood Pressure measurements were classified as hypertensive (systolic BP >140 mmHg) or normotensive. The abdominal aortic diameter was evaluated relative to the caudal vena cava and L1 vertebral body at three anatomical locations. Statistical comparisons were performed to assess differences between groups and potential confounding factors.

RESULTS

Neither the Ao/CVC nor the Ao/L1 ratio differed significantly between hypertensive and normotensive dogs (p = 0.393 and p = 0.229, respectively). However, the Ao/CVC ratio was significantly lower in anesthetized dogs (p = 0.03), whereas the Ao/L1 ratio remained unaffected. No significant differences in the ratio values were observed between the measurement sites. These findings suggest that systemic hypertension does not induce measurable abdominal aortic enlargement, which is detectable by CT.

CONCLUSION

This is the first study to evaluate CT-derived vascular indices as potential markers of systemic hypertension in dogs. The absence of significant differences shows that aortic diameter may not reliably reflect blood pressure status and that previous ultrasonographic findings may reflect venous variability or methodological artifacts rather than actual arterial changes. The Ao/L1 ratio may offer a stable, CT-specific metric for future vascular assessments. Prospective studies with direct modality comparisons are warranted.