Diethylstilbestrol (DES)

Overview

Diethylstilbestrol (DES) is a hormone classified as a synthetic, nonsteroidal estrogen. It is used primarily for treatment of urinary incontinence in spayed female dogs. It is thought that DES increases the responsiveness of the smooth muscle of the bladder neck to nerve activity, tightening the muscle and preventing leakage of urine. The hormone also has a stimulating effect on the reproductive system. 

Diethylstilbestrol is a prescription drug and can only be obtained from a veterinarian or by prescription from a veterinarian.

This drug is not approved for use in animals by the Food and Drug Administration but it is prescribed legally by veterinarians as an extra-label drug.

Brand Names and Other Names

This drug is registered for use in humans only.

Human formulations: None

Veterinary formulations: None

Diethylstilbestrol is no longer commercially available in some countries and is no longer a marketed drug in the United States; however, some veterinarians still have supplies of this drug and the drug can be obtained from compounding pharmacies.

Uses of Diethylstilbestrol

Diethylstilbestrol (DES) is prescribed for the treatment of hormonal responsive urinary incontinence in the spayed female dog. There are other drugs that also can be used in place of DES. However, DES may be the better choice in those pets that cannot tolerate phenylpropanolamine or ephedrine.

DES also has been used to prevent conception (pregnancy) after mismating (unplanned breeding) in dogs and cats. However, the drug is potentially dangerous for this use. 

DES has been used to treat estrogen responsive tumors, hyperplasia of the prostate gland and in perianal gland adenomas. However, neutering (castration) is the initial treatment of choice. 

Precautions and Side Effects

While generally safe and effective when prescribed by a veterinarian, diethylstilbestrol can cause side effects in some animals.

Diethlystilbestrol should not be used in animals with known hypersensitivity or allergy to the drug.

Diethlystilbestrol may interact with other medications. Consult with your veterinarian to determine if other drugs your pet is receiving could interact with DES.

Diethylstilbestrol should never be used in pregnant animals.

Estrogens at excessive doses, or in very susceptible animals, can depress the bone marrow, reducing the number of blood cells. This leads to decreased formation of platelets (needed for clotting), depressed white blood cell count (needed to fight infection), and reduced red blood cells (anemia). These effects can be prolonged or irreversible and fatal. 

Symptoms of an adverse effect include lethargy, depression, pale mucous membranes, abnormal vaginal discharge, loss of appetite and bleeding from the gastrointestinal and urinary tract.

Diethylstilbestrol can also increase the risk of uterine infections (pyometra) when given to intact (unspayed) female dogs. 

Animals receiving therapy with DES should be monitored monthly by a veterinarian.

Diethylstilbestrol has been involved in cases of immune mediated thrombocytopenia in dogs.

How Diethylstilbestrol Is Supplied

Diethylstilbestrol may be available through compounding pharmacies by prescription from your veterinarian.

Dosing Information

Medication should never be administered without first consulting your veterinarian. 

Dosing for prevention of conception after mismating: 0.1 to 1 mg per dog, orally for five days after mating. Some specialists argue that this drug should never be used for this purpose. 

Dosing for hormone responsive incontinence is typically 0.1 to 1 mg orally once a day for three to five days, then the dosage is reduced to 1 mg orally once a week. 

Periodic complete blood counts and platelet counts should be obtained in dogs receiving DES on a chronic basis. 

The duration of administration depends on the condition being treated, response to the medication and the development of any adverse effects. Be certain to complete the prescription unless specifically directed by your veterinarian. Even if your pet feels better, the entire treatment plan should be completed to prevent relapse or prevent the development of resistance.