Diethylstilbestrol
Diethylstilbestrol, or DES, is a synthetic nonsteroidal estrogen used principally for estrogen-responsive urinary incontinence in female dogs. Its main clinical application is improvement of urethral closure in selected spayed bitches with urethral sphincter mechanism incompetence. Although structurally different from steroid estrogens, it produces estrogen-receptor-mediated effects in responsive tissues.
Group
Nonsteroidal estrogen
Mechanism of Action
Diethylstilbestrol activates estrogen receptors and alters gene expression in estrogen-responsive tissues. In the lower urinary tract, estrogenic effects can improve urethral tissue support and vascularity and increase responsiveness to alpha-adrenergic stimulation. The resulting increase in urethral closure pressure can reduce involuntary urine leakage associated with urethral sphincter mechanism incompetence.
Dose Rates
Dog
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Urinary incontinence — Initial | 0.1–1 mg/animal | PO | Every 24 h | Up to 5 days; Individual amount depends on size and response. |
| Urinary incontinence maintenance | Reference only | PO | After the initial 5-day course, use the effective 0.1–1 mg per dog dose two or three times weekly; calendar schedule is not an exact hourly interval. | |
| Urinary incontinence induction and maintenance | Reference only | PO | Alternative course: 0.1–1 mg/dog daily for 5 days, then the lowest effective maintenance dose, commonly 1 mg weekly; the cited weekly maximum is 0.1 mg/kg. Weekly total-cap logic is not supported. | |
| Benign prostatic hyperplasia | 0.2–1 mg | PO | Up to 5 days; The source specifies a five-day course without an explicit repeat interval. | |
| Estrus induction | Reference only | PO | Historical staged protocol: 5 mg/day for up to 7 days; if ineffective, 10 mg/day for up to another 7 days. Continue only through the first two days of proestrus, then use a reproductive-hormone protocol. The cited LH/FSH amounts are for a 50–60 lb dog, not universal doses. Serious estrogen-associated marrow toxicity limits this approach. |
Cat
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Urinary incontinence | 0.05–0.1 mg/animal | PO | Every 24 h | |
| Estrogen-responsive incontinence — Initial | 0.1–1 mg | PO | Every 24 h | Up to 5 days; Females; maintenance alternative is 1 mg once weekly. Monitor for marrow toxicity. |
Indications
- Treatment of estrogen-responsive urinary incontinence in female dogs, especially spayed bitches with urethral sphincter mechanism incompetence.
Contraindications
- Food-producing animals
- Minimize human exposure because of carcinogenic potential.
Interactions
- May alter thyroid-binding proteins and thyroid replacement requirements.
Adverse effects
- Pyometra and estrogen-sensitive tumor risk
- Potential bone marrow suppression
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Diethylstilbestrol compounded/source-described tablet 1 mg | Tablet | 1 mg / tablet | PO |
| Diethylstilbestrol compounded/source-described tablet 5 mg | Tablet | 5 mg / tablet | PO |
Monitoring and Administration
Monitor CBC and clinical continence. Titrate to the lowest effective maintenance frequency; assess thyroid status when supplementation is used.