Female Canine Incontinence
Use of Diethylstilbestrol (DES) for therapeutic purposes
Urinary incontinence (UI) is defined as the involuntary loss of urine during the filling phase of the bladder . At this time, there are many suspected factors contributing to the problem. Nevertheless, urinary sphincter mechanism incompetence (USMI) after spaying is the most common micturition disorder, and its medical treatment is normally successful. The underlying mechanism is not fully understood. But, we do know that hormonal changes can induce structural and functional alterations in the bladder, as well as in the urethra composition. The proposed predispositions to incontinence that follows neutering including gender, breed, body weight, obesity, tail docking, spaying technique (ovariectomy and ovariohysterectomy) and morphology or position of neck of the bladder and urethral length, have all been investigated
To manage incontinent patients successfully, underlying abnormalities besides USMI should be ruled out. In the majority of cases, history, physical examination and laboratory tests including urinalysis and urine bacterial culture lead to a presumed diagnosis. If USMI is the cause, then further diagnostic tests should be discussed with the pet owner before starting therapy. There is no single technique that allows one to diagnose all causes of urinary incontinence and abnormal increased frequency of urination. The urinary tract has a complex anatomy and many nervous system connections to the urinary tract muscles, making diagnosis of the source of incontinence not an easy task. Please, refer to reference article Acierno, M. J., &Labato, M. A. (2006) for an image of urinary tract anatomy and nervous system connections. Possible advanced diagnostics that could be recommended are cystography, which is indicated for cases of abnormal urinary bladder position, size, or shape. Ultrasonography is best for mass effects, calculi, and other abnormalities. The combined cystography and excretory urography technique is recommended for diagnosing ectopic ureteral insertions. Computerized tomography and MRI imagings are indicated when the techniques described previously fail to elucidate the problem sufficiently
After diagnosis and confirmation of USMI is reached, medical approach is the mainstay of treatment for affected animals with surgical correction being considered when medical treatment fails to restore continence or patient is not suitable for long-term medication. For more information on surgical treatment options, please refer to Ponglowhapan, S., Khalid, M., & Church, D. (2012). Included in this article is list of medical options that could be chosen by the veterinarian depending on the degree of disease and concurrent chronic health conditions (see Table 1). A combination of one or more of these medications might be used for USMI depending on trial response. For this article, I will only discuss estrogen synthetic hormone medication used for USMI therapy.
Diethylstilbestrol (DES), a synthetic non-steroidal estrogenic stilbene derivative, is used as an aid in the control of USMI (idiopathic incontinence, hormone- responsive incontinence) in dogs. The mechanism of action of estrogen-like products like this one is increase in the responsiveness of urethral smooth muscle to the hypogastric nerves, thereby increasing muscle tone in the bladder neck and urethral sphincter. This re-establishes the maximal urethral closure pressure, restoring normal urethral function and continence.
In a study by Mandigers, R. J., & Nell, T. (2000), estriol, a naturally occurring short-acting estrogen, was used to treat acquired urinary incontinence in 129 female dogs selected by 48 veterinary practitioners in the Netherlands, Belgium, France and Germany. According to the veterinary practitioners 83 per cent of the dogs either became continent or improved, but the others showed no change or became worse. The owners reported similar results: 82 per cent of the dogs responded to treatment and the others did not. Mild and transient estrogenic effects such as swelling of the vulva and attractiveness to male dogs were observed soon after the treatment began and at the higher dose schedule used in 12 of the dogs. Other possible side effects of this medication are reversible lack of hair (alopecia), bone marrow toxicity (aplastic pancytopenia), and decrease platelet count (reversible thrombocytopenia) in blood test. But, platelet abnormalities could be physically seen as epistaxis (bleeding through nose), gastrointestinal hemorrhage, and ecchymoses or petechia (skin bleeding). If this occurs, please inform your veterinarian and visit an emergency clinic immediately. Regular bloodwork and recheck examinations are recommended during the use of this medication to adjust doses and prevent the discussed side effects. Because there is not enough information to establish a dose-response relationship, the following dose is administered proportional to the size of the dog and adjusted, based on clinical response: Oral, 0.1 to 1 mg total dose per dog every twenty-four hours for five days, then 0.1 to 1 mg total dose per dog one to three times a week, as needed to control incontinence. In the United States, diethylstilbestrol must be purchased from an approved source and compounded for veterinary use. Refer to the Animal Medicinal Drug Use Clarification Act, Food and Drug Administration regulations pertaining to compounding (CFR 21 Part 530.13), and the current Food and Drug Administration’s Compliance Policy Guide on Compounding of Drugs for Use in Animals.
Tablet 1: List of common therapeuthic options for urinary incontinence. Image from M.J. Acierno& M.A. Labato in Compendium (August 2006)
(1) Mandigers, R. J., & Nell, T. (2000). Treatment of bitches with acquired urinary incontinence with oestriol. The Veterinary Record, 149(25), 764-767.
(2) Reichler, I. M., &Hubler, M. (2014). Urinary incontinence in the bitch: An update. Reproduction in Domestic Animals, 49(s2), 75-80.
(3) Kahn, C. M., & Line, S. (9th Ed.). (2005). The Merck/Merial Manual For Pet. In Chapter: Noninfectious Urinary Diseases in Small Animals. Pages 1278-1279. Simon and Schuster.
(4) Abrams, P., Cardozo, L., Fall, M., Griffiths, D., Rosier, P., Ulmsten, U., ... & Wein, A. (2002). The standardisation of terminology of lower urinary tract function: report from the Standardisation Sub-committee of the International Continence Society. American journal of obstetrics and gynecology, 187(1), 116-126.
(5) Ponglowhapan, S., Khalid, M., & Church, D. (2012). Canine Urinary Incontinence Post-neutering: A Review of Associated Factors, Pathophysiology and Treatment Options. The Thai Journal of Veterinary Medicine, 42(3), 259.
(6) Sam, S., & Craig, D. L. (2000). The diagnosis of urinary incontinence and abnormal urination in dogs and cats. Veterinary Clinics of North America: Small Animal Practice, 30(2), 427-448.
(7) Acierno, M. J., &Labato, M. A. (2006). Canine incontinence. COMPENDIUM.
(8) Diethylstilbestrol (Veterinary-Systemic). © 2008 The United States Pharmacopeial Convention. Retrieved on June 9, 2016 from http://c.ymcdn.com/sites/www.aavpt.org/resource/resmgr/imported/diethylstilbestrol.pdf
Dr. Joanne Fernandez-Lopez is a small animal veterinarian graduated from North Carolina State University in 2014. She has been working at a small animal general practice in the South Miami Area. Recently, she accepted a position at a Small Animal Internal Medicine and Surgical internship in west Florida to pursue specialization. Her interest are dermatology, surgery, emergency medicine, exotic animal medicine, marine biology and research.