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 μm /μm [34-57 μm /μm]; P = .02), a thickened lamina propria (166 μm [73-336 μm]; P = .04), and smooth muscle fibrosis (42% [33%-78%]; P = .04) in horses with MMA when compared to controls horses (24 μm /μm [21-80 μm /μm]; 76 μm [36-176 μm]; 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.