Comparison of bronchoalveolar lavage findings and measurements of gas exchange during exercise in horses with poor racing performance.

This research article investigates the relationship between subclinical pulmonary disease and poor racing performance in Thoroughbred and Standardbred racehorses. They found that a higher count of total nucleated cells in the lung fluid and lower arterial oxygen levels during exercise could indicate pulmonary disease as a significant cause for lessened racing performance.

Overview of the Study

• The study involved twenty-four Thoroughbred and twelve Standardbred racehorses, aged between 2 and 6 years, that were reportedly performing poorly in races.
• Clinical exercise testing was performed on each horse, including an incremental speed exercise test on a treadmill inclined at a 10% slope. During the last 10 seconds of exercise at each speed, the researchers collected samples of arterial blood and expired gases.

Parameters Investigated

• The researchers determined multiple parameters from the collected samples, including maximum oxygen uptake and the partial pressures of oxygen and carbon dioxide in arterial blood.
• They also examined bronchoalveolar lavage samples (fluid from the lungs) for cytological findings like neutrophils (white blood cells), erythrocytes (red blood cells), and haemosiderophages (cells that have absorbed a blood pigment called haemosiderin), alongside the total nucleated cell concentration.

Key Findings

• The researchers discovered an inverse relationship between the total nucleated cell count in bronchoalveolar lavage samples and arterial oxygen partial pressure during exercise, which suggests that the presence of disease in the lungs may be a more important cause of poor racing performance than previously thought.
• Additionally, they noted a positive correlation between maximum oxygen uptake and the percentage of erythrocytes. Higher oxygen uptake could be linked to a higher presence of red blood cells, which are primarily responsible for carrying oxygen through the body.