Vertebral Heart Score (VHS) Calculator for Dogs and Cats
Calculate Vertebral Heart Score (VHS) from long-axis (L) and short-axis (S) measurements already transposed onto the thoracic vertebrae, and compare against dog and cat reference ranges.
Species
Long axis, L (vertebrae)
Ventral border of the carina to the cardiac apex, transposed onto the vertebrae from the cranial edge of T4.
Short axis, S (vertebrae)
Widest point of the cardiac silhouette, perpendicular to L, transposed onto the same vertebrae.
A screening aid, not a stand-alone diagnosis.
VHS is a screening aid, not a stand-alone diagnosis. A rising VHS on serial radiographs in the same patient is more diagnostically useful than a single absolute value, since normal baseline varies notably by breed and body conformation. Always interpret alongside clinical signs, breed, and other imaging findings.
How to use this tool
How VHS is measured
On a right lateral thoracic radiograph, measure the cardiac silhouette's long axis (L: from the ventral border of the carina to the cardiac apex) and short axis (S: the widest point perpendicular to L). Each measurement is then transposed onto the thoracic vertebrae starting from the cranial edge of T4, and expressed as the number of vertebral bodies it spans, to the nearest 0.1v. VHS = L(v) + S(v), reported as a single number in vertebral units (v).
Normal ranges
Dogs: approximately 8.5-10.5v (mean ~9.7v). Cats: approximately 6.6-8.1v (mean ~7.5v). Some breeds run higher at baseline without true cardiomegaly - Boxers commonly measure 11-13v, and deep-chested breeds in general trend higher - so breed-specific baselines and serial radiographs on the same patient are more reliable than one static cutoff.
Interpreting the result
A single high VHS raises suspicion for cardiomegaly but should always be interpreted alongside clinical signs, breed, and other imaging findings. A low VHS is far less clinically significant than a high one. The most useful application of VHS is tracking the trend for a given patient over serial radiographs, since a rising VHS is more diagnostic than any single absolute value.
Frequently asked questions
How is Vertebral Heart Score measured?
On a right lateral thoracic radiograph, measure the cardiac silhouette's long axis (L: from the ventral border of the carina to the cardiac apex) and short axis (S: the widest point perpendicular to L). Each measurement is transposed onto the thoracic vertebrae starting from the cranial edge of T4, expressed to the nearest 0.1 vertebra. VHS = L(v) + S(v).
What is a normal VHS in dogs and cats?
Dogs: approximately 8.5-10.5v (mean ~9.7v). Cats: approximately 6.6-8.1v (mean ~7.5v). Some breeds run higher at baseline without true cardiomegaly - Boxers commonly measure 11-13v, and deep-chested breeds in general trend higher, so breed-specific baselines matter more than one static cutoff.
Is VHS accurate for diagnosing heart disease?
VHS is a screening and monitoring aid that correlates with cardiac silhouette size - it is not a direct measure of cardiac function. False positives occur in deep-chested and barrel-chested breeds, and a falsely "normal" VHS can occur with pericardial effusion masking chamber-specific enlargement. Always combine VHS with an echocardiogram for a definitive diagnosis.
Why track VHS serially instead of relying on a single measurement?
An individual patient's own trend over time - especially alongside murmur grade and clinical signs - is a better indicator of progressive cardiomegaly than comparing one value to a population reference range, since normal baseline varies notably by breed and body conformation.