Bacterial isolates from tracheobronchial aspirates of healthy horses.

This research study examines the type of bacteria found in the respiratory tract of healthy horses, both racing and non-racing. It found that transient bacteria were more often found in pastured, non-racing horses while a significant number of thoroughbred racing horses had no bacterial growth.

Overview of the Study

• The study was conducted on tracheobronchial aspirates from 50 clinically healthy Thoroughbred racehorses and 36 pastured, nonracing racehorses. Tracheobronchial aspirates are samples collected from the horses’ respiratory tract and were used to identify and study the bacterial concentrations within.

Aerobic Bacteria with Recognized Pathogenicity

• 4 out of 50 (8%) of the Thoroughbred racehorses and 3 out of 36 (8%) of the pastured, non-racing horses were found to have aerobic bacteria with recognized pathogenicity. This means that some horses had bacteria that is known to cause diseases in their respiratory tract.

Transient Bacterial Isolates

• 12 out of 50 (24%) Thoroughbred racehorses and 23 out of 36 (64%) pastured, non-racing horses contained transient bacterial isolates. Transient bacteria are non-harmful bacteria that do not typically reside in the horse’s respiratory tract but may have been present due to environmental aspects or other temporary factors.

No Bacterial Growth

• 37 out of 50 (74%) Thoroughbred racehorses and 10 out of 36 (28%) pastured, non-racing horses had no bacterial growth in their tracheobronchial aspirates. This suggests that the majority of racing horses’ respiratory tracts were clear of bacterial growth.

Observations and Conclusions

• Notably, anaerobes, a type of bacteria that grows in absence of oxygen, were not isolated from any of the 12 sampled pastured horses.
• Transient bacteria were isolated more often in pastured, non-racing horses which can suggest that their environment exposes them to more varied bacteria.
• The results of this study contribute to the understanding of possible bacterial factors that can affect respiratory health in horses and may guide future preventive or treatment strategies.