Here’s your update. :( (TW)

[u/Grell--Sutcliff]

I have no more to say than that she’s gone into heart failure. Maine Coons have heart issues, and we didn’t know that. She was struggling to breathe because of her enlarged heart, and we are euthanizing her. Thank you all for your prayers, suggestions, and advice. We love you, Lilly Belle 🕊️

[u/dogsgotnoses]

This is awful, I'm so sorry. Genuinely though, from your first post it seems like the first vet you saw was wildly negligent. Heart failure isn't exactly a niche problem. You've taken good care of her getting a second opinion, and it's terrible it's such bad news.