Eosinophils in lung tissue in 2 Chilean Criollo horses with exacerbated recurrent airway obstructions “heaves”

Authors: ALEXANDER ORTLOFF, HUGO FOLCH, GABRIEL MORAN

Abstract: We report on 2 cases of recurrent airway obstruction (RAO) observed in Chilean Criollo horses aged 13 and 15 years. Both animals were classified as having severe RAO. The analysis of the recovered cells of bronchoalveolar lavage fluid (BALF) showed high percentages of eosinophils (82% and 80% in the differential cell counts of the 2 horses) and poor responses to bronchodilator and corticosteroid drugs. The histopathological lung evaluation showed eosinophilic infiltration in the peribronchial tissue, as well as in the lumen of the bronchi and bronchioli. In both horses, immunohistochemistry confirmed high p65 homodimer activity in bronchial cells. This report describes exacerbated heaves with eosinophilic infiltration and p65 activity in the lung tissue without any neutrophil infiltration, which is usually characteristic for this disease.

Keywords: Heaves, eosinophils, p65 homodimers, Chilean Criollo horses

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