Histologic investigation of airway inflammation in postmortem lung samples from racehorses.

This research investigates the airway inflammation in racehorses, using postmortem lung samples. The findings indicate common pathological changes in the small airways of racehorses that are in active racing or training.

Methodology

• The study was based on lung tissues obtained from 95 horses (Thoroughbreds, Standardbreds, and Quarter Horses), all of which had been actively racing or training.
• 10 standardized lung sections were examined postmortem from 37 horses, whilst 2 histologic sections of the caudodorsal lung lobes which were previously collected from 58 horses that died or had been euthanized during racing or training were also examined.
• The histologic sections were evaluated using a validated histologic small airway scoring system.

Results

• High scores were found for inflammatory cells, smooth muscle, and hemosiderin.
• The cause of death and signalment were not significant predictors of lung scores. However, the location of the lung sample proved to be a significant predictor. The highest scores were found in the caudal and dorsal sections.
• Inflammatory cell infiltration in peribronchiolar tissues, smooth muscle hyperplasia, and hemosiderin (prevalence of 86%, 98%, and 80%, respectively) were common findings in the lungs of these horses, with the caudodorsal regions being more severely affected.
• There was moderate correlation between smooth muscle hyperplasia and inflammatory cell infiltration. However, there was minimal correlation between hemosiderin and inflammatory cell infiltration.

Conclusion

• The study concluded that inflammatory airway disease has been identified through the use of bronchoalveolar lavage in young athletic horses throughout the world. The research detected pathological changes in the wall of small airways of horses that were actively training or racing.