Morphological findings in lungs of the horses with chronic obstructive pulmonary disease (COPD)

The frequency and characteristics of chronic obstructive pulmonary disease (COPD) based on morphological and cytological changes in equine lungs were studied in this paper. Lungs obtained from 51 horses of different age and sex were examined grossly and tissue samples were collected for pathohistological examination. Cytological examination was done on impression smears from the tracheal bifurcation. Pathohistological preparations were stained with hematoxylin eosin (HE), toluidine blue (TB), Giemsa staining, PAS staining and Pearls reaction for iron detection. The peroxidase anti-peroxidase technique was used to demonstrate CD3+ (T lymphocytes) and CD79+ (B lymphocytes). Tracheal bifurcation cytology impression smears were stained with hematoxylin eosin (HE), Giemsa staining and PAS staining. Pulmonary emphysema and lack of pulmonary collapse were the most common gross lesions whereas alveolar emphysema was described in 70.59% of all examined horses, more frequently in the distensive form (54.90%) and less frequently in the destructive form (15.69%). Pathohistological chronic bronchitis/bronchiolitis, with characteristic changes in the lumen, mucosa, submucosa and smooth muscle layer was described in all examined horses. Increased immunoreactivity was described in the lungs. The most common lesions seen on cytology impression smears from the tracheal bifurcation were thick, viscous, PAS positive mucus which forms Curschmann's spirals. The dominant cell population consisted of desquamated airway epithelial cells, as well as eosinophils, neutrophils, mast cells, erythrocytes and alveolar macrophages. Primary pulmonary pathogens as well as potential contaminants and secundary infection agens were isolated bacteriologically from lung samples. All the above-mentioned findings correlate pointing to the fact that chronic bronchitis/bronchiolitis represents the basic substrate of chronic obstructive pulmonary disease (COPD) which has a combined inflammatory and immunological etiology. Emphysema being secondary to airway obstruction.