Hi
and Hi to adorable Berry too. We have four black cats now (and another four cats) but black cats are pretty special aren't they
He's a very handsome lad
I'm so very sorry. You have to steal yourself for a rough ride I'm afraid
Learning to live with something that can take your beautiful boy at any time takes some getting used to i.e. you won't
We discovered that our 5 year old Boris was suffering from Hypertrophic Cardiomyopathy (HCM) last August. That led on to Chronic Heart Failure (CHF) involving first fluid outside the lungs and then within the lungs. I put my efforts into reading up on the condition and the latest research but he died on 7 December. A lot of the literature warned of a blood clot possibly causing pain but, when we found Boris, he was curled up and looked very peaceful. All the same it wiped us out for a while. Diuretics (Furosemide) and an attentive mom kept him alive for those 4 months.
It might help if Berry is an only cat so you can keep him quiet but diuretics administered 3 times a day at a sufficient dose to assist his breathing (and believe me you will get to know better than your vet what that dose should be) and as little stress as possible will be the order of the day. I was blessed with a sensible vet who encouraged me not to bring Boris in to the surgery too often as, whilst he was fairly docile, each visit was of course a stress he could do without. We were also "lucky" in that vet was able to xray our boy's lungs without sedation and he never had to have the fluid removed by needle. My hubby was the one that noticed our lads breathing seemed laboured so I guess we started diuretics in time to avoid using the needle. One thing I also learned is that, if appetite seems very poor, it could be a sign of potassium being too low.
As a 5 year old sharing a house with so many other cats, including his brother with whom he was used to playing, and he loved to go out; it made it difficult to keep Boris quiet and we resorted to locking him up for quite a while each day but of course that would stress him too.
This link will give you some info to start with
https://icatcare.org/advice/cat-health/cardiomyopathy-heart-disease-catsa more detailed and difficult to read link
http://www.msdvetmanual.com/circulatory-system/heart-disease-and-heart-failure/heart-failure#v3259558I hope you have much longer with your beautiful boy than we managed after diagnosis. It's a horrible condition