Effects of clenbuterol administration on serum biochemical, histologic, and echocardiographic measurements of muscle injury in exercising horses.

This study looked at the effects of clenbuterol (a bronchodilator) on cardiac and muscle health in horses who were exercised regularly. The results showed no significant negative impacts of clenbuterol on the horses’ health.

Study Design

• The study involved 12 healthy horses that were between 3 to 10 years old.
• These horses were split into two groups – a control group and a clenbuterol group each consisting of 6 horses.
• The control group received a saline solution while the clenbuterol group was administered up to 3.2 μg/kg of clenbuterol. Both treatments were given ever 12 hours orally for 14 days.

Exercise and Measurements

• All the horses in the study underwent submaximal treadmill exercise daily.
• Before and after the treatment period, muscle biopsy specimens were collected to determine the presence of cell apoptosis or programmed cell death.
• Various measurements were made throughout the study including serum clenbuterol and cardiac troponin I concentrations, as well as serum activities of creatine kinase and aspartate aminotransferase.
• Jugular venous blood samples were collected every 3 days and echocardiography was conducted every week starting from the day treatment began.

Results

• The findings showed that there were no significant effects of clenbuterol on the response variables measured between the control and clenbuterol-treated groups.
• No adverse outcomes were seen either within groups over the duration of the study.

Conclusion

• The results do not indicate any harmful effects of administering the approved dosage of clenbuterol on cardiac or skeletal muscle in the tested horses.