Mar Vista Animal Medical Center

3850 Grand View Blvd.
Los Angeles, CA 90066



(for veterinary information only)







Estrogens are potent female hormones produced naturally by the ovary and needed for the normal development of the female reproductive tract as well as for normal female fertility. Synthetic estrogens have, in the past, found assorted medical and industrial uses. In the 1960's researchers found that sphincter-related incontinence in post-menopausal women was alleviated with the administration of estrogens. Soon, the sphincter incontinence that is common in spayed female dogs was also being treated effectively with estrogen in the form of diethylstilbestrol (DES).

DES was originally used commercially as a growth promoting agent in livestock, as a human medication to help maintain pregnancy and in the treatment of prostate cancer in humans decades ago but was removed from these uses due to human safety issues. As the uses of DES dwindled to a few veterinary uses, its manufacturer found it unprofitable to continue its production and DES went off the market in the late 1990's. DES continued to be available to patients through compounding pharmacies which is fortunate because there was no FDA approved medication for canine urinary incontinence.

Recently this has changed with both phenylpropanolamine and estriol gaining FDA approval for canine incontinence. This article reviews estriol, which has been available to dogs in other countries for at least a decade but is relatively new for this use in the U.S. DES continues to be available through compounding pharmacies as before.



Several protocols have been published and tested regarding initial use of estriol for canine incontinence. They all come down to this: beginning at a daily dose for approximately two weeks and tapering to the lower dose each week until the minimum effective dose for the individual dog has been determined. At least seven days at each dose adjustment are needed to assess the dose. Approximately 90% of dogs will either be completely continent or significantly improved with this medication. The maximum dose of this medication is felt to be 2mg daily but if incontinence is not resolved after two weeks of this dosage then the diagnosis and treatment plan should be reconsidered.



The most common side effects of estriol were reduced appetite and vomiting. Appetite reduction was experienced in about 13% of dogs and vomiting in about 10%. Reducing the dose generally controls these issues.

One might expect effects related to the administration of female hormones to be seen in patients. They are but not with great frequency: swollen vulva (4% of patients), sexual attractiveness (3.5% of patients), breast enlargement and behavior consistent with being in heat (1%) of patients.

Estriol is a very short-acting female hormone which affords extra safety compared with other female hormones. Bone marrow suppression has been an issue with other estrogens but this has not been reported with short acting estrogens such as estriol at the very low doses needed to correct urinary incontinence.



The use of this medication may alter thyroid hormone levels.

This medication should not be used in combination with other estrogens or there may be an increased risk for hormone-related side effects, the worst of which being bone marrow suppression.

Concurrent use of phenobartital for may interfere with the effectiveness of estriol by enhancing its removal from the body.

Concurrent use of ketoconazole may elevate blood levels of estriol by interfering with its removal from the body. Similar issues occur with use of cimetidine (an antacid) and clarithromycin (an antibiotic).



Two tablets daily is felt to be the maximum dose for any dog and if this is not adequate to control incontinence, another therapy or further diagnostics should be elected.

Estriol should not be used during pregnancy and pregnant women should wash their hands after handling this medication.

Page posted: 10/17/201
Last updated: 5/26/2018