Table 1.

Modified New York Heart Association (NYHA) classification

Class	Clinical Correlate
I	Asymptomatic dogs with murmur but no cardiac failure
II	Clinical signs of congestive heart failure (exercise intolerance, dyspnea, cough…) during intense or extended physical activity
III	Clinical signs of congestive heart failure during mild physical activity
IV	Clinical signs of congestive heart failure present when resting