(E81) Bronchoalveolar Lavage Hemosiderosis in Lightly Active or Sedentary Horses

Abstract:

Background: Hemosiderophages in bronchoalveolar (BAL) cytology are commonly ascribed to exercise-induced pulmonary hemorrhage (EIPH); little information exists regarding the presence of these cells in horses that perform light or no work and referred for respiratory evaluation.

Objectives: To evaluate the presence of and predictors for hemosiderophages in BAL cytology of horses suspected of respiratory disease without history of or risk factors for EIPH.

Animals: BAL cytologies of 353 horses evaluated for respiratory disease between 2012 and 2022 at a referral center were retrospectively reviewed.

Methods: This was an observational retrospective cross-sectional study. Horses with a history or likelihood of past strenuous exercise were removed; the remaining 91 were classified as hemosiderin-positive (HSD-POS) or hemosiderin-negative (HSD-NEG) based on Prussian Blue staining. Potential predictors of the presence of hemosiderophages (history, clinical evaluation, baseline lung function, airway reactivity, BAL cytology and hemosiderin score) were compared between the two groups, using univariate and multivariate analyses.

Results: Horses with a diagnosis of severe equine asthma were significantly more likely to be HSD-POS than horses with mild-moderate equine asthma (odds ratio 11.1 (95% confidence interval [3.2 – 38.5]), p< 0.001).

Conclusions and clinical importance: Hemosiderophages were found in the BAL cytology in a subset of horses that perform light or no work and presenting for respiratory evaluation. The link between hemosiderophages and severe equine asthma may help elucidate previously unstudied pathology associated with equine asthma.