Fibrin/fibrinogen in lungs and respiratory secretions of horses with chronic pulmonary disease.

The research examines the concentration of soluble fibrinogen derivatives (SFD), along with protease and procoagulant activities in horse’s respiratory secretions that suffer from chronic pulmonary disease. It indicates a correlation between severity of disease, neutrophil content, and SFD concentration; and suggests that the presence of SFD might signify pulmonary inflammation.

Research Methodology

• The study involves determining the concentration of soluble fibrinogen derivatives (SFD), protease, and procoagulant activities in cell-free supernatants of equine respiratory secretions. These secretions were obtained from horses diagnosed with chronic pulmonary disease.
• Neutrophil concentration was estimated from direct smears of these secretions.
• Lung specimens and smears of the secretions were assessed for fibrin or fibrinogen presence using immunohistochemical methods.
• A total of 80 specimens were tested, with 35 found to contain SFD.

Findings

• It was found that respiratory secretions from horses suffering moderate or severe chronic pulmonary disease had SFD more frequently compared to those with mild disease.
• Secretions with a high number of neutrophils exhibited significantly higher SFD concentrations than secretions with fewer neutrophils.
• Protease and procoagulant activities in respiratory secretion specimens showed a positive correlation with neutrophil content, clinical diagnosis, and SFD concentration.
• Immunohistochemical evaluation revealed that macrophages stained for fibrin or fibrinogen were viewed in direct smears of respiratory secretions from horses with moderate to severe chronic small airway disease. However, they were absent in smears from mildly affected horses.
• Fibrin or fibrinogen was detected in a few thickened alveolar septa from horses with moderate or severe chronic small airway disease, but not in lungs from horses with mild or no evidence of chronic small airway disease.
• Fibrin or fibrinogen was identified in alveolar septa, granulomas, and on alveolar macrophages in lungs of all horses with chronic granulomatous and chronic bronchointerstitial pneumonia.

Conclusions

• The study concludes that the presence of SFD in equine respiratory secretions could be an indicator of pulmonary inflammation.