Clinical and necropsy evaluation of endocardial fibroelastosis in a mixed-breed cat with left side heart failure

A two-month-old, male intact, mixed-breed cat weighing 0.6 kg was presented with respiratory distress and anorexia. From the transthoracic echocardiographic, reduced fractional shortening (FS) and increased endocardial echogenicity were recognised with severe congestive heart failure (CHF). The kitten was administered an antibiotic and pimobendane under oxygen supplementation in an ICU cage. However, the respiratory condition worsened and the cat died the next day, and the subsequent necropsy and histopathology examinations confirmed endocardial fibroelastosis (EFE). There is a lack of information regarding the antemortem cardiac function evaluated by tissue Doppler imaging (TDI) in EFE cases. We report on the echocardiographic findings including the TDI in the EFE cat with a concomitant necropsy and histopathology confirmation in this paper. The echocardiographic findings showed presence of a ventricular false tendon within the left ventricle, a decrease in the left ventricular contractility (FS 11.1%, and a marked CHF). In this case, the echocardiographic findings were consistent with the human counterpart. However, these findings were like those of dilated cardiomyopathy and, hence, non-specific to EFE. As a result, veterinarians should keep in mind that endocardial fibroelastosis might be a possible reason for respiratory distress resulting from CHF with a low fractional shortening in young cats.