Human Chorionic Gonadotropine

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HYU-man ko-RI-on-ic go-nad-o-TRO-pin - Pronunciation guide

Brand Names

  • OvaCyst


Rx symbolHarvested from the urine of pregnant women, human chorionic gonadotropin is a hormone secreted by the placenta and is used by broodmare veterinarians to induce ovulation in mares. Because HCG usually causes ovulation of a mature follicle within 36 to 48 hours, this drug allows the mare to be bred at the optimal time for conception.


Human chorionic gonadotropin is used to time the breeding of mares to achieve optimal conception. By inducing ovulation, HCG enables broodmare veterinarians to obtain better results with fewer breeding attempts.

HCG is also used in the diagnosis of retained testicles by creating a measurable rise in testosterone in geldings exhibiting stallion-like behavior.

Dosage and Administration

Prescription medicationHuman Chorionic Gonadotropine
Method Dosage Concentration Period Duration
Intraveneous or Intramuscular injection 2000-3000 IU NA Treatment1 NA


  • Federal law restricts this drug to use by or on the order of a licensed veterinarian.
  • Extra-label use of drugs in treating animals is allowable only by licensed veterinarians within the context of a valid veterinarian-client-patient relationship, and does not include drug use in treating animals by the layman (except under the supervision of a licensed veterinarian).
  • 1Administration should take place with a preovulatory follicle of at least 35 mm in diameter (Perkins 1999)

Side Effects

No common side effects are reported in HCG use. Injection site reactions, such as pain and swelling, are infrequent and are usually relieved by hot compresses and nonsteroidal anti-inflammatory drugs. Rare anaphylactic reactions have been reported.


Most HCG preparations have a limited shelf life once they are reconstituted. Follow directions on label.

HCG is FDA-approved for use in cows. It is commonly used in horses and is accepted practice. HCG is a prescription drug, and U.S. federal law restricts this drug to use by or on the lawful written or oral order of a licensed veterinarian.

HCG should not be given in early pregnancy, as it may cause embryonic death.

Repeated use of HCG may cause antibody formation in the mare. Mares with high antibodies may not respond reliably to HCG.

There are no indications for HCG use in competition horses. Check with the individual regulatory group.


None noted in literature.


No information noted in literature.


OvaCyst PowderOvaCyst Powder



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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.