ABSTRACT
Respiratory distress or labored breathing is characterized by exaggerated breathing effort relative to the degree of physical activity or physiologic demand. Dyspnea is defined as ‘undue awareness of breathing or awareness of difficulty in breathing’. This term is therefore inappropriate for describing veterinary patients and the terms labored breathing, increased respiratory effort, or respiratory distress are preferred. Labored breathing can result from impaired gas exchanges secondary to obstruction of conducting airways, failure of the muscles and/or structures responsible for ventilation, pulmonary disease, or cardiac disease. Increased respiratory effort in response to pain, hyperthermia, and metabolic acidosis is not associated with gas exchange abnormalities. Diseases causing a decline in blood oxygen content (e.g. anemia) do not usually stimulate breathing except in cases of severe anemia when tissue hypoxia results in increased anaerobic metabolism and lactic acidosis.
