Equine pulmonary disease: a case control study of 300 referred cases. Part 3: Ancillary diagnostic findings.

The majority of 270 adult horses with chronic pulmonary diseases had excessive volumes of respiratory secretions (RS) present in their trachea, elevated tracheal RS neutrophil ratios and lowered arterial oxygen partial pressures. Some control horses, had inexplicably elevated trachael RS neutrophil ratios. Only the chronic obstructive pulmonary disease (COPD) affected group had significantly elevated bronchoalveolar lavage fluid (BALF) neutrophil ratios. Maximal intrapleural pressure changes (max dPpl) were raised in 48% of COPD cases and rarely with other pulmonary disorders. Arterial pH or carbon doxide partial pressures values were seldom altered with any pulmonary diseases. Tracheal RS and BALF eosinophil ratios were raised with lungworm infection and idiopathic pulmonary eosinophilia.