Mitral dysplasia with papillary muscle atrophy in a dog

A 9-month-old, female, mixed-breed dog was presented with dyspnea, exercise intolerance and a left apical heart murmur. Echocardiography revealed mitral systolic regurgitant flow by morphological abnormalities of the mitral apparatus including dilated annulus, excessively asymmetric mitral leaflets, short and stout chordae tendinae, and atrophic papillary muscles. The dog was diagnosed with congenital mitral dysplasia based on the echocardiographic features. Two months later, the dog died and the echocardiographic findings were confirmed by necropsy. This case report describes the echocardiographic features of mitral dysplasia with papillary muscle atrophy, and compares the gross necropsy findings in a dog.