Alveolar macrophage graded hemosiderin score from bronchoalveolar lavage in horses with exercise-induced pulmonary hemorrhage and controls.

This research study investigates the use of a scoring system for measuring hemosiderin content in alveolar macrophages collected through bronchoalveolar lavage in horses to detect exercise-induced pulmonary hemorrhage (EIPH). It concludes that this process may be more effective than the currently used method of post-exertional endoscopy of lower airways.

Objective of the Research

• The primary purpose of this study was to evaluate if a quantitative scoring mechanism for assessing the hemosiderin content in alveolar macrophages, cells within the lungs, could provide a more sensitive method for identifying exercise-induced pulmonary hemorrhage (EIPH) in horses.
• This was compared to the current screening method of post-exertional endoscopy of the bronchial airways.

Methodology of the Study

• The study was conducted on a sample of 74 Standardbred racehorses who were divided into either the control group (no evidence of EIPH) or the EIPH group based on their medical history and repeated post-exertional endoscopic evaluations.
• Bronchoalveolar lavage, a medical procedure in which a bronchoscope is passed through the mouth or nose into the lungs to obtain cells and fluid for analysis, was performed on the horses.
• The extracted alveolar macrophages were stained with Perl’s Prussian blue, a method used to detect iron in tissue samples, and scored for hemosiderin content using a method known as the Golde scoring system, to obtain the total hemosiderin score (THS).

Findings of the Study

• This research revealed that all subjects had some level of hemosiderin present in the alveolar macrophages. However, there was a significant difference in the distribution of cells across the various grades between the control group and the EIPH positive horses.
• They found that using a THS of 75 as a cutoff point, the THS test had a sensitivity of 94% and a specificity of 88% – indicating that it was able to correctly identify those with and without the disease with high accuracy.
• The level of agreement between the test’s results and the EIPH status was very good—signifying a high level of reliability of the THS test for identifying horses with EIPH.

Conclusion of the Research

• The study concluded that by carefully assessing and scoring alveolar macrophages for hemosiderin content using the Golde scoring system, this could offer a more sensitive technique for detecting exercise-induced pulmonary hemorrhage (EIPH) over traditional repeated post-exertional endoscopy.