Diethylstilbestrol For Veterinary Use
by Barbara Forney, VMD

	Overview Therapeutic Class Synthetic Estrogen (nonsteroidal) Species Dogs, Cats Commonly prescribed by vets for: Urinary incontinence, mismating, prostatic hypertrophy, treatment of estrogen responsive neoplasias, induction of heat.

Basic Information

Diethylstilbestrol (DES) is a synthetic estrogen. Estrogen is one of the primary ovarian hormones and the pharmacologic actions of DES mimic those of estrogen. These include development and maintenance of female sexual organs and secondary sex characteristics. Estrogens affect the release of pituitary hormones, affecting lactation, ovulation, androgen and other hormone secretion. They have some mild anabolic effects and have multiple effects on the skeletal system including increasing calcium deposition, bone formation, and accelerating epiphyseal closure. Estrogen can also increase sodium and water retention. DES is well absorbed from the gastrointestinal tract.

Dogs and Cats

DES is primarily used to treat urinary incontinence in spayed females. Estrogens increase urethral tone and help to prevent leaking or dribbling of urine. DES is usually effective for this purpose and the risk of side effects is relatively low due to the small dose. DES may be used with the alpha-agonist phenylpropanolamine. These drugs behave in a synergistic fashion.

DES has been used for the prevention of pregnancy due to accidental breeding or mismating in dogs and cats. It is not generally recommended for this purpose, as it is not very effective. DES is used in the management or treatment of prostatic hypertrophy. The definitive and preferred treatment for prostatic hypertrophy is castration but in cases where that is not an option, a short course of DES has been shown to markedly reduce prostatic secretion for up to 2 months. The risk of adverse effects increases with multiple treatments. DES is also used in the treatment of certain hormonally responsive tumors including perianal gland adenoma although this use is controversial due to side effects. DES has also been used experimentally in combination with other hormones for inducing estrus. Different protocols combine DES with LH, FSH and HCG. This work is still experimental and not widely clinically used.

Side Effects

• The most serious side effect of estrogen therapy is bone marrow suppression and toxicity that may progress to a fatal aplastic anemia. Estrogen toxicity manifests itself first by a leucocytosis, followed by bone marrow depression with anemia, thrombocytopenia, and leukopenia. Blood dyscrasias and changes in the peripheral blood smear may be evident by 2 weeks. Although this serious adverse effect is more common after large or repeated doses, it may occur at the recommended dose. Side effects are more common in older animals. Because of the potential toxic side effects of estrogen use, it is always important to use the lowest effective dose for the shortest period of time.

• Other side effects include signs of estrus, lethargy, diarrhea, vomiting, vaginal discharge, pyometra, polydypsia, polyuria, and feminization of male dogs.

Precautions

• DES and other estrogens should not be used during pregnancy as it has been shown to cause fetal malformations.

• Daily administration of DES in cats resulted in lesions in the pancreas, liver and heart. Estrogens have been shown to be carcinogenic in laboratory animals.

Drug Interactions

• Rifampin, phenobarbital, and phenylbutazone may decrease the activity of DES due to microsomal enzyme induction.

• DES and other estrogens may enhance corticosteroid activity. The corticosteroid dose may need to be adjusted.

• DES and other estrogens may decrease the activity of anticoagulants.

Overdose

Overdose in humans resulted in nausea, vomiting and bleeding.

About the Author

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 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.

You can purchase books by Dr. Forney at www.exclusivelyequine.com

	What are the available dosage forms from Wedgewood Pharmacy? Click here to see the different ways our pharmacists prepare this medication for your patients. Call us at 1-888-678-1967 to speak with a pharmacist for other special requests or to prescribe.

The information contained on this site is general in nature and is intended for use as an informational aid. It does not cover all possible uses, actions, precautions, side effects, or interactions of the products shown, nor is the information intended as medical advice or diagnosis for individual health problems or for making an evaluation as to the risks and benefits of using a particular product. You should consult your doctor about diagnosis and treatment of any health problems. Information and statements have not been evaluated by the Food and Drug Administration ("FDA"), nor has the FDA approved the products to diagnose, cure or prevent disease.

Wedgewood compounded veterinary medicines are not intended for use in food and food-producing animals.

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