Cat has been sick a month, no improvement; X-ray shows an enlarged heart and pericardial effusion — what medicine?

The X-ray shows an unclear heart outline with no displacement, and the lateral view shows lung lobes compressed by pleural fluid causing incomplete expansion and rounded rear lobes, indicating pleural effusion. But pericardial effusion cannot be confirmed by X-ray alone; it only suggests possible heart failure or myocarditis.

Confirm heart disease or pericardial effusion with a cardiac ultrasound, which measures effusion volume and heart structure to guide later thoracentesis. If the cat shows abdominal breathing, dyspnea or panting, give oxygen first and reduce stress.

If ultrasound shows pericardial or pleural effusion causing distress, sedate and perform pericardiocentesis and thoracentesis to relieve breathing. Once the cause is confirmed, treat the primary disease.