Checkers, an 11 year old spayed female papillon, was presented to Cornell University Hospital for Animals Emergency Service for severe dyspnea and presumptive congestive heart failure. There was no history of lethargy or cough, however the referring veterinarian noted a murmur and an arrhythmia. Upon presentation to Cornell, Checkers was dyspneic and tachypneic with bilateral crackles, and tachycardic with a left-sided systolic murmur. Based on a clinical picture suggestive of congestive heart failure, furosemide therapy was initiated. However, Checkers was unresponsive and she continued to deteriorate with even more aggressive treatment. Following Checkers' failure to improve, an echocardiogram was performed, leading to a diagnosis of severe pulmonary hypertension. Checkers responded well to treatment with sildenafil and pimobendan, and there was marked improvement in her respiratory rate and effort as well as her heart rate. Checkers was discharged to the care of her owner, and she continued to improve at home, however her long term prognosis remains guarded.