Re: CHF detectable with stethoscope?
- CHF is definitively diagnosed by x-ray, never by stethoscope. If a cat has previously been diagnosed with severe heart disease (based on echocardiogram) and is having trouble breathing, it's reasonable to think the cat has gone into CHF but to 'prove it' you would need an x-ray. The cat may or may not have crackles, and may or may not have muffled heart or lung sounds.
Cats in CHF can have fluid three places: in the lungs (pulmonary edema, sometimes causes crackles), around the lungs (pleural effusion, sometimes causes muffling of chest sounds), or within the heart sac (pericardial effusion -- no symptoms by stethoscope because when associated with CHF, there is only scant effusion). We don't worry about (or hear about) the pericardial effusion that much because it is scant and doesn't make a difference in terms of treatment.
So the answer to your question is, no. If you are looking for signs at home, count resting respiratory (breath) rates regularly and look for changes. That is the #1 thing you can do at home.