Tracheobronchoscopic Assessment of Exercise-Induced Pulmonary Hemorrhage and Airway Inflammation in Barrel Racing Horses.

BACKGROUND: Poor performance is often suspected to be associated with EIPH in barrel racing horses; however, there are no published reports of EIPH for this discipline. The prevalence of EIPH in barrel racing horses is also unknown. OBJECTIVES: This study was performed to determine the prevalence of EIPH and signs of airway inflammation in barrel racing horses under normal racing conditions in Alberta. ANIMALS: About 170 barrel racing horses. METHODS: Observational cross-sectional study. Tracheobronchoscopic examinations were performed at least 30 minutes postrace. Video recordings were scored off-site independently by two observers for EIPH and tracheal mucus accumulation (TMA). Horses with an EIPH score ≥2 were not assessed for TMA. Interobserver agreement was calculated by weighted κ statistics. Run times, environmental variables, and clinical information were also recorded for analysis. RESULTS: 77/170 (45.3%) of horses examined showed evidence of EIPH (grade ≥ 1). Interobserver agreement was 0.94. 140/141 (99.3%) of horses assessed for TMA showed evidence of tracheal mucus accumulation (grade ≥ 1) with 104/141 (73.8%) having a TMA score ≥ 2. Interobserver agreement was 0.73. A weak positive association was found between EIPH scores and average run speed, the presence of cough at rest reported by the riders, increased recovery time, exercise intolerance, and outdoor pattern. CONCLUSIONS AND CLINICAL IMPORTANCE: The high prevalence of EIPH observed in the sampled population indicates that barrel racing induces substantial stress on the lungs. The presence of EIPH did not impact negatively on performance. Factors such as environmental dust and frequent traveling might have contributed to the high prevalence of TMA observed.

Endoscopic assessment of airway inflammation in horses.

BACKGROUND: Comprehensive endoscopic scoring of the upper and lower airways for inflammation has not been critically assessed among a large population of horses. The relationship between upper and lower airways described in humans by the "one airway, one disease" concept might also apply to horses. HYPOTHESIS/OBJECTIVES: To evaluate if an association exists between endoscopic inflammatory scores and mucus scores of upper and lower airways and to investigate if endoscopic findings correlate with the lower airway inflammation measured by bronchoalveolar lavage (BAL) cytology. METHODS: Prospective field study. Pharyngitis, pharyngeal mucus, tracheal mucus, tracheal septum thickness, and bronchial mucus were scored using new and previously described scoring systems on a convenience sample of 128 horses with and without lung inflammation. Based on BAL fluid cytology, horses were categorized as having normal, moderate, or severe inflammation of the lower airways. RESULTS: All 5 endoscopy scores showed excellent interobserver agreement. Tracheal mucus (P < .001), tracheal septum thickness (P = .036), and bronchial mucus (P = .037) were significantly increased in horses with severe inflammation BALs and were correlated among themselves but not with upper airways scores. BAL neutrophils percentage was correlated with tracheal mucus (r(s) = 0.41, P < .001), bronchial mucus (r(s) = 0.27, P = .003), and had a weak negative correlation with pharyngitis (r(s) = -0.25, P = .004). CONCLUSIONS AND CLINICAL IMPORTANCE: Lower airway endoscopy scores are reflective of lower airway inflammation; however, upper and lower airways are independent in terms of severity of inflammation. Therefore, observing upper airway inflammation is not an indication to test for lower airway inflammation.