Bronchoalveolar lavage in horses: effect of exercise and repeated sampling on cytology.

This research investiages the effect of exercise and repeated sample collection on bronchoalveolar lavage cytology in Thoroughbred racehorses. The study found that the exercising group had lower leukocyte concentrations than rested horses and higher erythrocyte counts and haemosiderin scores, but physical exertion did not generate inflammatory responses in the bronchoalveolar lavage fluid.

Study Design and Groups

• The researchers conducted bronchoalveolar lavage (BAL) procedures at weekly intervals for a duration of 10 weeks on a sample size of 10 Thoroughbred horses under race training (referred to as group 1).
• A control group of four rested horses (group 2) was also included in the study for comparison.
• A subset of four horses from group 1 continued to participate in the study for an additional nine weeks (this group was called group 3).

Measurements and Findings

• From the collected BAL samples, the researchers performed cytological analysis, which included leukocyte counts, erythrocyte counts, differential leukocyte counts, and haemosiderophage scoring.
• Analysis showed that the mean leukocyte concentration was significantly lower in the race training group (group 1) when compared with the rested horses (group 2). The differential leukocyte data, however, did not illustrate significant differences between the two groups.
• A substantial level of variability was observed in the macrophages and lymphocytes percentage in the differential counts, with no clear trends observed.
• The study detected a tendency for the proportion of neutrophils to decrease over time for both groups 1 and 2.
• The erythrocyte counts and haemosiderin scores were significantly higher in the race training group compared to the rested horses.

General Conclusions

• The overall results of the study showed that neither vigorous exercise nor the repetitive BAL sampling itself invoked an inflammatory response in the bronchoalveolar lavage fluid.
• This study can aid in improving the understanding of BAL cytology in physical exertion contexts and the impact of exercise and sampling repetition on horses in race training.