The “inflammatory airway disease” (IAD) is a very common syndrome in young
racehorse in training. Clinical signs are subtle including decreased performance, mild exercise
intolerance and chronic cough. The purpose of the present study is to determine the incidence of
1) mucus accumulation, 2) tracheal neutrophylia and 3) tracheal infection with streptococci
among poor performing, chronically coughing Standardbred horses. Streptococcus equi subsp
zooepidemicus and Streptococcus pneumoniae was not always associated with mucus or high
neutrophils percentage but the higher number of bacteria was found in horses with the higher
mucus score. Nevertheless, the role of streptococci in IAD of Strandardbred horses and
involvement of other etiological agents needs further investigations
