It’s funny that this is up, I had 2 dogs in the past year present very similarly- lethargic, brick red mucous membranes and with a high PCV, but no dehydration. Everything else normal. They were both older dogs. I googled, as you do, and polycythemia came up as a possibility. Unfortunately, I have no follow up on either dog, but one of the treatments listed was blood letting. This sounded the very opposite of elegant medicine, but would this be an ’emergency’ solution if the animal was struggling? Not to detract from the cat’s case, and curious to hear the outcome.
I would agree, cat radiograph- cardiomegaly- especially right sided?
