Diethylstilbestrol (DES) is a synthetic estrogen medication used in veterinary medicine, primarily for dogs. It is a prescription drug, often compounded by specialty pharmacies, and its use is specific and carefully managed by veterinarians. While DES has a notable history in human medicine, its current application in canine health is distinct and limited to particular conditions.
Understanding Diethylstilbestrol (DES)
Diethylstilbestrol (DES) is a synthetic compound that mimics natural estrogen. Estrogens are hormones that influence various bodily functions, including bladder control. DES works by increasing the responsiveness of urethral smooth muscle, thereby enhancing muscle tone in the bladder neck and urethral sphincter. This action helps to improve the ability of the bladder to hold urine.
Historically, DES was used in human medicine but was discontinued due to concerns. However, its use in veterinary medicine for dogs is considered safe and effective when administered at very low doses under professional supervision. The extremely low doses used in canine therapy significantly reduce the risk of the side effects seen with higher doses or in human applications.
Primary Applications in Canine Medicine
The primary application of DES in canine medicine is managing estrogen-responsive urinary incontinence, especially in spayed female dogs. After spaying, a decline in natural estrogen levels can weaken the urethral sphincter, leading to involuntary urine leakage. DES strengthens these muscles, restoring bladder control. It is effective in 60-80% of treated dogs.
Veterinarians typically start with a daily dose for a short period, often one week, to establish control. Once continence is achieved, the medication is tapered to the lowest effective dose, which may be given as infrequently as once a week or even less often. DES may also be combined with other medications, such as phenylpropanolamine (PPA), for better control in dogs that do not respond sufficiently to either alone. While less common, DES has also been historically used to manage prostatic hypertrophy in male dogs, though its main focus remains urinary incontinence in females.
Potential Side Effects and Important Considerations
While generally well-tolerated at low doses, DES can have potential side effects. Milder effects may include changes in appetite, lethargy, or mild vaginal spotting in unspayed females. Serious, though rare, adverse effects are typically associated with higher dosages or prolonged use. These include bone marrow suppression, which can lead to life-threatening aplastic anemia. This condition involves a decrease in the production of red blood cells, white blood cells, and platelets, making the dog susceptible to infection, fatigue, and bleeding issues.
Rare but serious side effects can also include uterine infections (pyometra) in intact females or the development of mammary or ovarian tumors. Regular veterinary check-ups and blood tests, such as complete blood counts (CBCs), are important to monitor for adverse changes, particularly bone marrow function. Owners should immediately contact their veterinarian if they observe symptoms like unusual bleeding, bruising, fever, pale gums, increased thirst, or lethargy. Accurate dosing and never exceeding the prescribed amount are important for minimizing risks. Pregnant women should exercise caution and wear gloves when handling DES due to potential human toxicity.
Alternatives and Management Strategies
For dogs experiencing urinary incontinence, several alternatives and management strategies exist beyond DES. Phenylpropanolamine (PPA) is a commonly prescribed medication that works differently from DES by strengthening the urethral sphincter muscles through a different pathway. PPA has a high success rate, often between 74-90% in female dogs. Another estrogen compound, estriol (brand name Incurin), is also available and FDA-approved for canine incontinence, offering a short-acting estrogen option.
Surgical options, such as colposuspension or urethral bulking injections, may be considered for dogs that do not respond to medical therapies. These procedures aim to physically improve the structural support or bulk around the urethra to enhance bladder control. Non-pharmacological management strategies can also play a role, including establishing more frequent potty breaks, providing absorbent bedding, and managing the dog’s weight to reduce pressure on the bladder. The most appropriate treatment approach depends on the individual dog’s condition, and a veterinarian can help determine the best course of action.