Radiographic and echocardiographic measurement of the heart in obese cats

A prospective study was undertaken to reconcile radiographic cardiomegaly a nd normal echocardiography in obese cats and to test a radiographic techniq ue for better distinguishing between pericardial fat and the heart. Ten obe se, but otherwise normal cats and 10 non-obese normal cats were used. A bod y condition scoring system was used to objectively group obese and non-obes e normal cats. Two-dimensional echocardiograms were made to verify that all cats had a normal heart. Thoracic radiographs then were made using standar d and altered exposure techniques. The hearts were measured on these radiog raphs using the metric and a vertebral scale system, Obese cats consistentl y had excessive fat around the heart especially if they also had a large am ount of falciform fat. Altering exposure technique by increasing mAs and de creasing kVp sometimes enhanced the radiographic contrast between fat and m yocardium. Enhanced radiographic contrast accentuated the double silhouette identifying the true cardiac silhouette within the fat expanded silhouette , Pericardial fat usually was distinguished more readily in lateral than in VD radiographs. In two cats, pericardial fat had a characteristic prominen t square corner to the right cranial margin of the cardiac silhouette in VD radiographs. Obesity caused increased width and depth of the thoracic cage , 2D echocardiograms revealed normal cardiac dimensions in both groups of c ats and increased precordial distance in the obese group.