Ultrastructural findings in horses with chronic obstructive pulmonary disease (COPD). I: Alterations of the larger conducting airways.

The research article investigates the microscopic alterations in the conducting airways of horses with Chronic Obstructive Pulmonary Disease (COPD), with specific focus on changes in ciliated cells and the correlation of these findings with the severity of the clinical diagnosis.

Methodology and Sample Selection

• The researchers conducted comprehensive studies using light and electron microscopes to look at the conducting airways in a total of 36 horses.
• Out of the total sample, 28 horses were noted to have varying degrees of clinically manifested COPD.
• Eight other horses, considered to have normal lungs, were used as a control group for comparison.

Key Findings

• The main ultrastructural alteration was found in the ciliated cells. These cells which usually have small hair-like structures, were lost in focal areas.
• These lost cells were replaced by undifferentiated cells in a predominantly hyperplastic (overgrown) epithelium, implying abnormal cell growth.
• The horses, irrespective of the disease’s severity, exhibited various types of ciliary malformation – changes in the structure of the cilia.
• Findings also revealed swollen intercellular clefts and an increase in mast cells, interpreted as signs of nonspecific mucosal hyperreactivity.
• Interstitial cells with unknown cause crystal inclusions in the cytoplasm were observed in many horses.

Correlation between Clinical Diagnosis and Microscopic Findings

• Partial correlation was observed between the clinical diagnosis and the morphological findings, more specifically, in the ciliary loss and the presence of intracytoplasmic crystal inclusions.
• In approximately 43% of cases (12 of 28 cases), the severity of clinical diagnosis matched the degree of the morphological findings.

Interpretation and Conclusions

• The alterations in the conducting airways were interpreted as reactive processes to changes in the smaller airways because of equine COPD.
• This could suggest that changes at the microscopic level in the conducting airways could throw light on the progression and severity of COPD in horses.