Lower respiratory tract disease in Thoroughbred racehorses: Analysis of endoscopic data from a UK training yard

Summary Reasons for performing study: There has been much research directed at potential causative agents and the epidemiology of lower respiratory tract disease (LRTD), but few reports of the clinical progression and outcome. Objectives: To define clinical features of LRTD in racehorses, including association with age and average duration of disease, through the analysis of endoscopic data. Methods: A retrospective analysis of records from a single training yard of endoscopic examinations undertaken over a 2‐year period was performed. Horses were subjected to regular endoscopic examination for a variety of reasons, and all horses placed on antibiotic therapy for lower respiratory tract disease were rescoped following treatment. Data analysed included a 0–8 tracheal mucus score based on visible endoscopic mucus and gross tracheal lavage turbidity, as well as age and treatment duration and type. Results: A total of 522 endoscopic examinations undertaken on 123 horses and tracking 169 episodes of lower respiratory tract disease were recorded. Mean duration of disease episode was 15.5 days (median = 11 days, range = 4–61 days). Horses age 2 years were significantly more likely than those age ≥3 years to have at least one episode of respiratory disease (P