Anabolic Steroids

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AN-a-bol-ik STER-oids - Pronunciation guide

Brand Names

  • Equipoise (Boldenone)
  • Winstrol V (Stanozolol)


Rx symbolAnabolic steroids are a class of drugs that are related to the male hormone, testosterone. These drugs help rebuild tissues that are weakened due to disease, injury, or surgery. Anabolic steroids are used in equine medicine for building weight and muscle mass, and to alleviate anemia. In the race horse industry, many consider the use of anabolic steroids as a means to improve speed and win more races.

Recent scientific studies show that anabolic steroids have not proven to be of benefit to the horse. These studies are at odds with the conventional thinking and anecdotal evidence that supports their use in the performance horse industries, specifically racing. Because of the stigma associated with the use of anabolic steroids in human athletes, there is much higher scrutiny in the non-therapeutic use of these drugs as performance-enhancers.

An excellent technical paper on the use of anabolic steroids to improve performance in horses is “Pharmacokinetics of Boldenone and Stanozolol and the Results of Quantification of Anabolic and Androgenic Steroids in Race Horses and Non Race Horses,” by Soma et al (Journal of Veterinary Pharmacology and Therapeutics, 2007).

Anabolic steroids are persistent drugs with effects that last up to several weeks following the last dose. As prescription drugs subject to the Anabolic Steroid Control Act, federal law restricts the use of these drugs without orders from a licensed veterinarian.


Anabolic steroids such as stanozolol and boldenone are synthetic derivatives of the male hormone, testosterone. They are labeled for usage with debilitated or weakened animals, and are prescribed to stimulate appetite, increase weight gain, strength, and vigor.

Dosage and Administration

Prescription medicationAnabolic Steroids
Method Dosage
(click row for calculator)
Concentration Period Duration
Intramuscular injection 0.5 mg/lb Boldenone 50 mg/ml Every 3 weeks 1 or 2 treatments
Intramuscular injection 25 mg/100lb Stanozolol 50 mg/ml Every week Up to 4 weeks


  • Federal law restricts this drug to use by or on the order of a licensed veterinarian.
  • Not for use in horses intended for food.
  • Calculator is for educational purposes only. Follow your veterinarian's instructions regarding use of this, or any medication.

Side Effects

Anabolic steroids in equines can cause increased aggressive and dominant behavior. They can also impair fertility and cause fillies and mares to show masculine behaviors. In stallions, anabolic steroids may shrink the size of the testicles and lead to lower sperm production. In young horses, anabolic steroids may affect normal bone growth.


Anabolic steroids should be used with caution in breeding animals. There are indications that these drugs should not be used with animals that have heart, liver, or kidney problems.

Stanozolol and boldernone are FDA-approved for use in horses. They are prescription-only drugs and controlled substances. U.S. federal law restricts the use of these drugs by or on the lawful written or oral order of a licensed veterinarian.

Anabolic steroids are prohibited in any drug-free competition. It is important to check the rules with each specific regulatory group.


Anabolic steroids may increase the effect of anticoagulants, such as warfarin.


No specific information on overdose is found.


Equipoise Anabolic Steroid Injection Equipoise Anabolic Steroid Injection


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About the Author

EquiMed Staff

EquiMed staff writers team up to provide articles that require periodic updates based on evolving methods of equine healthcare. Compendia articles, core healthcare topics and more are written and updated as a group effort. Our review process includes an important veterinarian review, helping to assure the content is consistent with the latest understanding from a medical professional.