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Chronic clenbuterol administration negatively alters cardiac function
Margaret M Sleeper1, Charles F Kearns, Kenneth H McKeever
1University of Pennsylvania, School of Veterinary Medicine, Philadelphia, PA, USA.
Medicine and Science in Sports and Exercise
|April 5, 2002
Summary
Chronic clenbuterol administration, even at therapeutic levels, significantly increased cardiac dimensions and wall thickness in mares. This suggests a potential negative impact on cardiac function and an increased risk of aortic rupture.
Area of Science:
- Veterinary Cardiology
- Equine Exercise Physiology
Background:
- Beta2-agonists at pharmacological doses can induce cardiac toxicity.
- Limited data exist on the cardiac effects of chronic clenbuterol use in horses.
Purpose of the Study:
- To investigate the impact of therapeutic clenbuterol levels on cardiac performance in horses.
- To assess cardiac function changes following chronic clenbuterol administration with or without exercise.
Main Methods:
- Twenty unfit Standardbred mares were assigned to four groups: clenbuterol plus exercise (CLENEX), clenbuterol alone (CLEN), exercise alone (EX), and control (CON).
- Echocardiography was used to measure cardiac size and function before and after 8 weeks of treatment and exercise protocols.
Main Results:
- Both CLENEX and CLEN groups showed significant increases in left ventricular dimensions and interventricular septal and posterior wall thickness.
- Aortic root dimensions were significantly increased in the CLENEX and CLEN groups, indicating a potential risk for aortic rupture.
Conclusions:
- Chronic administration of clenbuterol, even at therapeutic levels, may adversely affect cardiac structure and function in horses.
- These findings suggest that clenbuterol use could increase the risk of serious cardiovascular events like aortic rupture.