Airway remodeling in horses with mild and moderate asthma

Background There is a remodeling of the central airways in horses with severe asthma but whether a similar process occurs in horses with the mild or moderate asthma (MMA) is unknown. Objectives To evaluate lesions affecting the central airways of horses with MMA. Animals Twelve horses with MMA and 8 control horses. Methods Case-control retrospective study of horses classified as MMA affected or controls based on history and bronchoalveolar lavage fluid cytology. Endobronchial biopsies were analyzed using histomorphometry and a semiquantitative histologic scoring system. Results Histomorphometry identified epithelial hyperplasia (47 mu m(2)/mu m [34-57 mu m(2)/mu m]; P = .02), a thickened lamina propria (166 mu m [73-336 mu m]; P = .04), and smooth muscle fibrosis (42% [33%-78%]; P = .04) in horses with MMA when compared to controls horses (24 mu m(2)/mu m [21-80 mu m(2)/mu m]; 76 mu m [36-176 mu m]; and 33% [26%-52%], respectively). The semiquantitative score results indicated, in horses with MMA, the presence of epithelial hyperplasia (7 of the 12 horses with MMA and only 1 of the 8 control horses had a score of 1/1), and submucosal inflammatory leucocytes in the central airway (11 of the 12 horses with MMA and only 4 of the 8 control horses had a score >= 1/2). Conclusions and Clinical Relevance Tissue remodeling of the bronchial lamina propria, epithelium, and smooth muscle was present in horses with MMA.

Automated summary

The study found evidence of tissue remodeling in the bronchial lamina propria, epithelium, and smooth muscle of horses with mild to moderate asthma.