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Estrone for Veterinary Use

by Barbara Forney, VMD

Basic Information

Estrone is a naturally occurring form of estrogen. In the horse, it is produced by the ovaries, placenta, and testis. Estradiol is the dominant estrogen in mares and is responsible for sexual behavior. There is very little scientific study of exogenous estrone use, but this drug has been used for many years based on anecdotal information and general knowledge regarding the basic properties of estrogens.


Exogenous estrone is administered to performance horses, particularly geldings, as a possible preventive for exercise-induced pulmonary hemorrhage (EIPH) and for its mild anabolic-effects. Stress failure of pulmonary capillaries is one hypothesized component in the pathogenesis of EIPH. The rationale for estrone use in these circumstances is that estrogens may reduce capillary bleeding and accelerate clot formation. Unfortunately estrone and other estrogens have not been effective to treat this major health-problem of racehorses.

There are veterinarians who use estrone on a regular basis for its mild anabolic properties. Although estrogens are only mildly anabolic, they do not have the adverse behavioral side-effects sometimes seen with other anabolic steroids. In fact, estrogens are thought to be mood-enhancing in most species, causing some horse owners to attribute improvements in attitude, weight gain, and way of going to estrogen/estrone supplementation.

Estrone Side Effects

No side-effects have been reported when estrone is used with performance horses.


Estrogens should not be used in the pregnant mare.

Drug Interactions

The effects of glucocorticoids may be enhanced when used with estrogens. The dose of corticosteroids may need to be reduced.


No information regarding acute overdose or toxicity was found in the literature.

For Veterinary Practices
For Pet & Horse Owners


Therapeutic Class


May Be Prescribed by Vets for:
Exercise-induced pulmonary hemorrhage, mild anabolic steroid.

Search for Available Dosage Forms

About the Author

Dr. Barbara Forney

Barbara Forney, VMD

Dr. Barbara Forney is a veterinary practitioner in Chester County, Pennsylvania. She has a master's degree in animal science from the University of Delaware and graduated from the University of Pennsylvania School of Veterinary Medicine in 1982.

She began to develop her interest in client education and medical writing in 1997. Recent publications include portions of The Pill Book Guide to Medication for Your Dog and Cat, and most recently Understanding Equine Medications published by the Bloodhorse.

Dr. Forney is an FEI veterinarian and an active member of the AAEP, AVMA, and AMWA.