Three-hundred adult horses, referred from 1990 to 1993 inclusively, for pulmonary examination were assessed using standardised history taking and clinical, intrapleural pressure, arterial blood gases and pH, bronchoscopic and tracheal and broncho-alveolar lavage fluid (BALF) cytological examinations. Two-hundred and thirty-five cases were referred with overt signs of pulmonary disease and the remaining 65 cases were referred for pulmonary examination because of reduced exercise (usually racing) performance or prolonged dyspnoea after racing.
No pulmonary disease was detected in 30 cases. The 270 horses with pulmonary disease included 148 cases (54.8%) of chronic obstructive pulmonary disease (COPD), 45 (16.7%) of infectious or post infectious pulmonary disease, 7 (2.6%) of Streptococcus zooepidemicus pulmonary infection, 7 (2.6%) of lungworm infection, 16 (5.9%) of primary exercise induced pulmonary haemorrhage (EIPH), 9 (3.3%) of chronic idiopathic hypoxaemia, 20 (7.4%) of miscellaneous identified pulmonary disorders and 18 (6.7%) of undifferentiated pulmonary disorders. Two cases of primary summer associated obstructive pulmonary disease (SPAOPD) were observed, but 9.5% of COPD affected horses additionally suffered from SPAOPD.