Acquired left-to-right shunting through a valve-incompetent foramen ovale in a cat with hypertrophic cardiomyopathy and congestive heart failure.

To our knowledge, this is the first report of an acquired left-to-right shunt through a valve-incompetent foramen ovale in a cat with hypertrophic cardiomyopathy. Severe left atrial dilation was suspected to cause interatrial shunting through the valve-incompetent foramen ovale, and this finding may be relevant to echocardiographic evaluations in other cats.