The cat is neutered. 5-in-1 vaccine done every year. Loss of appetite and energy from 1 week ago, accelerated respiration ultrasounds revealed pulmonary effusion. We performed thoracocentesis to remove 100ml of pleural fluid, whose TP was 3-2. Smearing included an increased number of lymphocytes (we are waiting on cytodiagnosis at the moment). We suspect atelectasis in the left lung from x-ray images. What would be your diagnosis? Please tell me your thoughts.