Clenbuterol and the horse revisited

Vet J. 2009 Dec;182(3):384-91. doi: 10.1016/j.tvjl.2008.08.021. Epub 2008 Oct 16.


Clenbuterol is a beta(2)-agonist and potent selective bronchodilator that is used to treat bronchospasm in the horse. The drug is normally administered to horses orally as a syrup formulation. Once absorbed into the systemic circulation, clenbuterol has the potential to cause many side effects, including a repartitioning effect and major alterations in cardiac and skeletal muscle function. Recent studies have also reported that clenbuterol can affect bone and the immune, endocrine and reproductive systems. A great deal of information has been published on the beneficial effects of short term therapeutic doses of clenbuterol on the equine respiratory system, although there is limited information about chronic administration, particularly since this has been associated with adverse physiological effects on other systems. This review summarizes the relevant understanding of clenbuterol for clinicians and horse owners who may administer this drug to pleasure and performance horses.

Publication types

  • Review

MeSH terms

  • Adrenergic beta-Agonists / adverse effects*
  • Adrenergic beta-Agonists / therapeutic use
  • Animals
  • Bronchial Diseases / drug therapy
  • Bronchial Diseases / veterinary
  • Clenbuterol / adverse effects*
  • Clenbuterol / therapeutic use
  • Dose-Response Relationship, Drug
  • Heart Diseases / chemically induced
  • Heart Diseases / veterinary
  • Horse Diseases / chemically induced*
  • Horse Diseases / drug therapy
  • Horses
  • Muscle, Skeletal / drug effects
  • Oxygen Consumption / drug effects
  • Physical Conditioning, Animal / physiology*


  • Adrenergic beta-Agonists
  • Clenbuterol