Monthly, daily, and circadian variations of measurements of pulmonary mechanics in horses with chronic obstructive pulmonary disease.

The research study is about understanding the temporal variations of lung function in healthy horses and those with chronic obstructive pulmonary disease (COPD) and exploring if improvements to airway blockage could be predicted by the response to atropine administration.

Research Methodology

• The study involved a total of 12 horses; 7 with COPD and 5 healthy ones who served as control group.
• The researchers performed pulmonary function tests on these horses at different intervals: monthly for 3 consecutive months, daily for 5 consecutive days, and every 6 hours for a 24 hours period before and after administering atropine, a medication used to promote lung relaxation and airflow.
• The horses were also evaluated after spending 5 consecutive months at pasture, that is, out in the field.
• Several parameters related to respiratory function such as respiratory rate, tidal volume (the amount of air moved into or out of the lungs during each ventilation cycle), minute ventilation (the total amount of air moved in and out of the lungs per minute), maximal change in transpulmonary pressure, pulmonary resistance, and pulmonary elastance were measured and analysed.

Research Findings

• The results showed that COPD-affected horses had a significantly higher expiratory to inspiratory time ratio and higher values of other respiratory metrics such as maximal change in transpulmonary pressure, pulmonary elastance and resistance than the control group, throughout all time periods.
• Significant daily variation in tidal volume and monthly and circadian variation in lung stiffness (measured as pulmonary elastance) were observed in horses with COPD, while in control horses, significant changes were apparent only in the ratio of time spent exhaling to inhaling during daily recordings.
• Administering atropine and performing maintenance on pasture led to significant reduction in several key respiratory metrics in horses with COPD, suggesting improvements in pulmonary function.

Conclusions

• The study concluded that despite variations in respiratory mechanic measurements in both healthy horses and those with COPD, the values remained distinctly different between the two groups over time.
• Measurements were also found to be repeatable over both short and long time periods, despite individual variation among horses.
• Furthermore, it was found that the administration of atropine to horses with COPD understated the improvement in respiratory function seen after the horses had been kept at pasture.