Suspected sequential left atrial ruptures in a dog with myxomatous mitral valve disease

An 11-year-old mixed breed dog was presented with exercise intoler-ance , syncope. At admission, transthoracic echocardiography revealed myxoma-tous mitral valve disease (MMVD) associated with severe left atrial (LA) enlargement and moderate anechoic pericardial effusion with a hyperechoic den-sity suggestive of a thrombus. Rupture of the LA free wall secondary to MMVD was suspected , medical therapy with furosemide and pimobendan was in-itiated. After one month, recheck echocardiography showed mild anechoic pericar-dial effusion and an acquired atrial septal defect with a left-to-right intracardiac shunting flow. In light of the dog's history, the latter finding was suspected to be secondary to a further rupture of the LA wall due to MMVD, this time affecting the interatrial septum. The images described here allow us to suspect that sequen-tial LA wall ruptures developed over time in the same subject affected by MMVD, a clinical presentation not previously described in veterinary medicine.(c) 2022 Elsevier B.V. All rights reserved.