Influence of climatic changes on respiratory health in a teaching herd of outdoor-housed horses.

The research paper investigates the influence of climatic changes on the respiratory health of horses, specifically an outdoor teaching herd in southern Brazil. The researchers analyzed respiratory symptoms and airway responses across different seasons to conclude that even horses living outdoors experience seasonal respiratory changes.

Study Design

• The study was carried out on 17 horses from a teaching herd. All the horses were housed outdoors year-round in southern Brazil. Except for one horse with a history of severe asthma, all animals were considered healthy.
• The study period involved the winter, spring, and summer seasons. For each of these periods, the horses underwent physical examinations and lower airway tests.
• Airway endoscopic evaluation included scoring for tracheal mucus and bronchial septum thickness. Bronchoalveolar lavage fluid (BALF) was collected at three points during the study, while bronchial septum biopsies were carried out only during the spring and summer.

Results and Analysis

• Statistical analysis included repeated measures ANOVA (which assesses differences in mean scores under different conditions) and Wilcoxon tests to reveal significant variations.
• The tracheal mucus score and the septal thickness did not differ across seasons. However, cytological analysis of BALF showed distinct seasonal patterns. The mean percentage of neutrophils (white blood cells that fight off infections) was higher in spring than summer, and the eosinophil count (a type of disease-fighting white blood cell) was higher in winter than in spring and summer.
• The bronchial septum biopsies revealed no noticeable differences between the spring and summer seasons. Furthermore, no correlations were established between these histopathological observations and the BALF analyses.

Conclusions

• The findings suggest that outdoor horses exhibit respiratory changes associated with different seasons, pointing to a need for deeper investigation. This is a significant observation considering that outdoor horses are believed to experience a less allergenic environment compared to stabled ones.
• The use of bronchial septum biopsies did not make a significant contribution to the clinical diagnosis in this study.