ABSTRACT
Horses are athletic animals and use only a small proportion of their respiratory capacity at rest. Respiratory rate should be evaluated prior to stimulating the horse. Normal expiratory effort is mostly elastic thoracic recoil with barely detectable abdominal movement. If respiratory effort is easily detectable at rest it is likely that the horse has dyspnoea. There is normally little or no noise during inspiration at rest and light exercise; there may be noise on expiration related to vibration of the false nostril. Fat or unfit horses may make a respiratory noise; this disappears as fitness increases. In normal adult horses there is little audible noise in any part of the lung field. The audible area of the lung field may be expanded in horses with severe recurrent airway obstruction or decreased ventrally if there is pleural effusion or pulmonary consolidation. Lung biopsy is rarely undertaken in horses as it has a number of complications including epistaxis, pneumothorax and sudden death.
