Prospective pre- and post-race evaluation of biochemical, electrophysiologic, and echocardiographic indices in 30 racing thoroughbred horses that received furosemide.

The research conducted a systematic study on 30 thoroughbred horses to understand the effects of a high-level race on their cardiac function, electrophysiologic parameters, and certain biochemical markers of heart dysfunction. This was done before and after racing when horses also received furosemide, a drug often used in horse racing industry to prevent pulmonary bleeding.

Objective of Study

• The research had dual objectives of understanding how a high-intensity race affects horses’ cardiac health and generating reference intervals by measuring cardiac health parameters before and after the race.
• These reference intervals were compiled to guide in the preparation of screening practices for race horses in future.
• This detection method aid in early identification and prevention of exercise induced cardiac fatigue (EICF) and cardiac dysrhythmias, potentially life threatening heart conditions that have been detected in high-intensity human athletes.

Procedures and Test Conducted

• The test took into account physical exams, ECGs, and echocardiograms of these horses before the race and within half to one hour after the race.
• Blood samples were also collected at the start of the race, immediately after the race, and 4 and 24 hours after the race.
• These blood samples were studied for their electrolyte composition, hematocrit level, cardiac troponin I level, and partial pressure CO2 values.

Results

• The study concluded that the heart rate significantly increased after the race, by a median difference of 49 bpm.
• However, no dysrhythmias or abnormal rhythms were noted in the ECG assessment.
• There was an increase in the number of horses showing a regurgitation in the aorta and AV valves following the race.
• The systolic function, which was measured by fractional shortening, was significantly increased after the race.
• Cardiac troponin I levels remained the same during pre- and immediately post-race examinations, but increased significantly 4 hours after (T4) the race than reduced to baseline level 24 hours after (T24) the race.

Conclusions and Implications

• While individual horses served as their own controls in this research, the study was not able to rule out the potential effect of regression to the mean.
• The reference intervals gathered in this study can be used to identify echocardiographic and electrocardiographic abnormalities in racing horses receiving furosemide.
• This study provides valuable insights in understanding the impact of high-intensity races on the cardiac health of horses and potentially in developing preventive measures against cardiac ailments in racing thoroughbreds.