Abstract

Dilated cardiomyopathy is relatively common in captive flying foxes. Quantitative measurements were determined that could be used to diagnose cardiac disease and describe the appearance of normal and abnormal thoracic radiographs in these animals. Lateral and ventrodorsal thoracic radiographs from 66 apparently healthy flying foxes of three species (Rodriguez island flying fox, Pteropus rodricensis, n=18; small island flying fox, P. hypomelanus, n=16; Malaysian flying fox, P. vampyrus, n=32) were evaluated. Absolute and relative cardiac dimensions were measured and the radiographs subjectively evaluated to describe the cardiac appearance in relation to other thoracic structures. The same methods were applied to radiographs from nine flying foxes with confirmed cardiomyopathy. The following ratios were most efficient in categorizing cardiac silhouette size: in the ventrodorsal projection, heart width to thoracic width and heart width to clavicle length, and in the lateral projection, heart width compared to thoracic height. On the ventrodorsal projections, heart width was on average 55% the width of the thorax and 95% the length of the clavicle. On a lateral projection, heart width was 75% thoracic height and heart length was 110% thoracic height. When radiographs from the bats with known dilated and acute cardiomyopathy were compared to those of apparently healthy animals, the apicobasilar heart length compared to thoracic height and heart width compared to thoracic height on lateral films were the most sensitive ratios for diagnosing cardiomegaly.