I am sorry to hear you are worried about your Persian. I am a veterinarian and will do my best to help. I am sorry to see you have not gotten help from an expert until now. I just came online and saw your question.
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How long has he been not eating? He is probably not pooping, because he is not eating. Is there any vomiting?
Blood tests tell us a lot, but not everything. We don't learn much about the pancreas, intestines, heart, and some of the glands, or if a pet has cancer on a basic blood panel. Pancreatitis is fairly common in older cats. Unfortunately so is cancer. If I had an older cat that was not eating, and blood tests did not tell me why he is not eating, my next step would be to do an ultrasound to look at pancreas, intestines, etc. Even Xrays might be helpful, if only blood tests were done.
Hiding, and not eating, are two ways that cats tell us they are sick, that they do not feel good. He is telling us that something is wrong, and I would do some more tests to find out where his problem is.
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