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My name is***** I am sorry to hear about your kitty and that he is sick. I am very concerned about the fluid in the chest, outside the lungs. This unfortunately is most commonly caused by cancer in the chest but can also be a bacterial infection. Your regular veterinarian did the right thing by sending the fluid to the lab for analysis.
Cats are very good at hiding their illness, so I am not surprised that you did not notice any symptoms beside sneezing. In the wild, predators would eat them if they appeared sick, so it is in their best interest to hide illness. I would recommend waiting for the results from your regular veterinarian before doing anything more. Sometimes a second opinion can be helpful, so that is a reasonable course to pursue as well.
Best of luck to you and Norman.
I hope this answer helps you. Feel free to contact me if you have any further questions.
Kansas State University
College of Veterinary Medicine Class of 2001