Clinical improvement was noted in all horses involved in the clinical trial , but the group that received PUFA had greater improvement in clinical signs ( cough score improved 60 % ) , lung function ( respiratory effort decreased 48 % ) , and BALF ( neutrophils decreased from 23 to 9 % ) when compared to placebo ( cough score improved 33 % , respiratory effort decreased 27 % , BALF neutrophils increased from 11 to 17 % ; P < .05 ) .