A systematic review and meta-analysis of the efficacy of furosemide for exercise-induced pulmonary haemorrhage in Thoroughbred and Standardbred racehorses.

Abstract: Furosemide is the most commonly used medication for exercise-induced pulmonary haemorrhage (EIPH); however, critical evaluation of the strength of evidence for efficacy of furosemide is lacking and is warranted so that evidence-based treatment decisions can be made. Objective: To evaluate the efficacy of furosemide to reduce the severity or frequency of detection of EIPH in Thoroughbred and Standardbred racehorses. Methods: Systematic review with meta-analyses. Methods: Primary studies were identified via searches of electronic databases, relevant texts and reference lists of published articles. Studies were not restricted by date or publication status. Only studies published in English were eligible for inclusion. Searches were performed using a predetermined search string. Randomised controlled trials, nonrandomised trials and observational studies were included. Three authors independently assessed each study using the Cochrane collaboration guidelines and Grading of Recommendations Assessment, Development and Evaluation recommendations for rating quality of evidence. Meta-analysis of studies was performed with pooled data to determine whether furosemide reduced the frequency of detection of EIPH (yes or no) as evaluated by tracheobronchoscopy or bronchoalveolar lavage fluid red blood cell number, or if furosemide reduced the severity of EIPH by at least one tracheobronchoscopic grade. Results: Seventeen studies fulfilled the inclusion criteria. The relative risk of detecting any EIPH by tracheobronchoscopy after administration of furosemide was 0.88 (pooled data from 11 studies, n = 5780; 95% confidence interval 0.79-0.97, P = 0.01). When data from only high-quality randomised controlled trials (2 studies, n = 405) were used, the relative risk of detecting endoscopically evident EIPH was 0.68 (95% confidence interval 0.58-0.79, P<0.001). The proportion of horses previously diagnosed with EIPH having a reduction of at least one EIPH grade after furosemide was 68% (2 studies, n = 405; 95% confidence interval 61-78%). Conclusions: There is high-quality evidence, albeit limited, that administration of furosemide reduces the incidence and severity of EIPH in Thoroughbred or Standardbred racehorses.