Acute respiratory distress in dogs and cats is a common presenting complaint and can be life-threatening. Early identification of unstable patients and timely therapeutic intervention are essential to limit compromise of tissue oxygenation and deterioration in condition. Oxygen supplementation, appropriate drug therapy, thoracocentesis, thoracostomy tube placement, emergency tracheostomy and positive pressure ventilation (PPV) may be required to relieve respiratory distress. It is important to consider signalment and history, assess posture, observe the pattern of respiration and perform an initial physical examination focused on the cardiorespiratory system. Based on these findings, a clinical estimation of the anatomical location of the problem can guide initial therapy. The chapter looks at General principles of therapy; Specific drug therapy; Ventilation; and Ancillary procedures.