Comparison between conventional and applied vertebral heart score (VHS) methods to evaluate heart size in healthy Thai domestic shorthair cats

Abstract

Thoracic radiography is the most common first modality for heart size evaluation and confirming cardiogenic
pulmonary edema in cats with suspected heart diseases. The Vertebral Heart Score (VHS) was established as an
objective method for diagnosing cardiomegaly via thoracic radiography. However, the conventional VHS method is
inappropriate for cats with abnormal thoracic vertebrae. Therefore, the applied VHS method, which uses the lateral
view axis sum divided with the length of each thoracic vertebra (T4, T5 and T6) was created to minimize the limitation
of VHS in these cases. This study compared the conventional and the applied VHS methods in healthy Thai domestic
shorthair cats to evaluate the heart size of cats with abnormal thoracic vertebrae or improper thoracic vertebral
alignment.
Right lateral (RL) and left lateral (LL) radiographs were taken of 97 clinically healthy adult Thai domestic shorthair
cats, and the VHS was measured on both RL and LL views. Applied VHS was calculated by using the summation of
cardiac long and short axis divided by the length of each thoracic vertebra (T4, T5 and T6). The mean±SD values of
VHS were 7.2 ± 0.45 v. (LL) and 7.43 ± 0.44 v. (RL). The mean±SD of applied VHS of T4, T5 and T6 in LL view axis were
7.17 ± 0.48 v, 7.11 ± 0.47 v and 7.03 ± 0.47 v respectively, while the mean±SD of applied VHS of T4, T5 and T6 in RL
view were 7.43 ± 0.47 v, 7.38 ± 0.46 v and 7.29 ± 0.47 v respectively. No statistical difference between the mean of
conventional VHS compared to the mean of applied VHS for both LL and RL view were found from ANOVA testing.
Results indicated that differences between conventional VHS and applied VHS of both LL and RL view axes were
not significant. Therefore, applied VHS methods might provide increased accuracy for evaluation of heart size in cats
with abnormal thoracic vertebrae. However, suitability of the applied VHS methods in different cat breeds requires
further investigation.