Left atrial rupture in a dog with degenerative mitral valve disease

An eight-year-old female Chihuahua-mongrel was presented after cough-induced collapse. Thoracic radiographs revealed cardiomegaly and mild pulmonary oedema. Echocardiographic examination revealed pericardial effusion, caused by an atrial rupture. Marked mitral regurgitation, dilation of the left atrium and ventricle were indicative of myxomatous mitral valve disease as the underlying cause of the atrial rupture. The dog was admitted for oxygen therapy, cage rest and further management. She responded well and was discharged 2 days later. A re-examination was performed one week after discharge, showing resolution of the pericardial effusion. The dog's heart failure treatment was adjusted. The owners reported that the dog was doing well and back to normal. Nevertheless, 44 days after initial presentation, she was presented to the emergency service due to acute pulmonary oedema secondary to ruptured chordae tendineae. There was no evidence of a relapsed atrial rupture. As the dog did not respond to treatment of acute heart failure, the owners decided to have her put to sleep.