Assessment of survey radiography as a method for diagnosis of congenital cardiac disease in dogs

In order to assess the diagnostic accuracy of survey radiography for canine congenital cardiac anomalies, thoracic radiographs of 57 dogs with congeni tal cardiac anomalies, 31 normal dogs and 27 dogs with acquired cardiac dis ease were mixed, and reviewed by two Independent observers, who were blinde d to any patient information. The congenital anomalies were aortic stenosis (n=25), pulmonic stenosis (n=10), patent ductus arteriosus (n=9), ventricu lar septal defect (n=8), tricuspid dysplasia (n=3) and mitral dysplasia (n= 2). Both observers were moderately accurate at identifying dogs with cardia c disease. Their ability to distinguish dogs with congenital versus acquire d cardiac disease was poorer and this assessment was probably Influenced by the recognition of patients that were skeletally immature, which biased ob servers towards a diagnosis of congenital cardiac anomaly. The diagnosis ra te for specific congenital anomalies was also poor (the differential list i ncluded a correct diagnosis In only 40 and 37 per cent of cases). Radiograp hic signs of specific cardiac chamber enlargement or pulmonary vascular abn ormalities were recognised by both observers In only 20 per cent of instanc es in which they might be expected. They were, however, recognised more fre quently in dogs with anomalies that imposed a volume load on the heart than in dogs with anomalies that induced a pressure load on the organ. It is co ncluded that survey radiography Is an inaccurate method for diagnosis of ca nine congenital cardiac anomalies because of the difficulty of recognising radiographic signs, which are not present in many cases.