Respiratory distress is a medical term that refers to both difficulty in breathing, and to the psychological experience associated with such difficulty, even if there is no physiological basis for experiencing such distress. The physical presentation of respiratory distress is generally referred to as labored breathing, while the sensation of respiratory distress is called shortness of breath or dyspnea. Respiratory distress occurs in connection with various physical ailments, such as acute respiratory distress syndrome, a serious reaction to various forms of injuries to the lung, and infant respiratory distress syndrome, a syndrome in premature infants caused by developmental insufficiency of surfactant production and structural immaturity in the lungs.
Symptoms may be outwardly evident, physically labored ventilation or respiratory efforts; clinically evident inability to adequately ventilate and/or oxygenate. This is currently the preferred term to use in referring to veterinary patients who present with severe respiratory difficulty
See also 
- Respiratory Distress Veterinary Emergency and Critical Care Medicine. Colorado State University. Revised April 14, 1998