A cough can occur from many causes. Unfortunately, the type of cough (or even what a veterinarian hears with their stethoscope) does not tell us the cause of the cough.
Likely not heart disease: A cough that occurs in a pet with a normal breathing rate (see above) is less likely to be due to heart disease.
Likely heart disease: A cough that occurs in a pet with a sleeping breathing rate of > 30 breathes/min is at a high risk of having heart disease – or some other urgent cause of poor airway/lung function