A 4-year-old spayed female indoor-only domestic shorthair cat was evaluated at the University of Wisconsin because of a 1-week history of progressive respiratory difficulty. The cat was being treated by the referring veterinarian with antimicrobials (metronidazole and orbifloxacin) as well as furosemide, with a resultant slight initial improvement in clinical signs. However, radiographic views obtained by the referring veterinarian after initiation of treatment revealed a dorsally deviated and compressed trachea, pleural effusion, and middle lung lobe consolidation.
On the day of the referral evaluation, the cat became anorectic and developed respiratory distress. On physical examination, the