Acute respiratory distress syndrome (ARDS) or acute lung injury (ALI), is a severe, life-threatening condition characterized by widespread inflammation in the horse's lungs. The condition is most often caused by sequela of sepsis or significant trauma but can also result from a primary respiratory infection such as from Rhodococcus equi infections. ARDS prevents oxygen from getting to the horse's lungs and into the blood. Most humans who have this condition receive oxygen from a breathing machine; however, it isn't a practical treatment for horses suffering from ARDS.