Hormone-related urinary incontinence is a very common problem in adult and senior female dogs that have been spayed. The problem can arise months or years after the procedure.
Typically these dogs urinate normally, but there is urine leakage during rest. Blood and urine tests are usually normal in these pets.
Incurin, manufactured by Merck Animal Health, increases the resting muscle tone of the urethra. According to Veterinary Practice News:
In a study of 226 spayed female dogs, a greater percentage of dogs treated with Incurin improved compared to dogs treated with placebo. Incurin was shown to be effective for the control of estrogen-responsive urinary incontinence in spayed female dogs 1 year and older.
There are a lot of reasons for urinary incontinence or urine dribbling in dogs, so if your canine companion has started leaking a bit, the first order of business is an appointment with your vet to determine the underlying cause.
It's true that in spayed female dogs the most common reason for urine dribbling is hormone-induced. However, it's extremely important to rule out all other possible reasons for incontinence before deciding it's hormonal in nature.
Hormone-related incontinence has been compared to bedwetting, since it is common for dogs with the condition to leak urine during periods of relaxation and/or sleep.
Incurin by Merck Animal Health
Incurin has been in use in other countries for years. It is actually identical to the human drug Ovestin, which since the late 1950's has been prescribed for peri- and post-menopausal women in Europe and other countries (but not the U.S.).
The important thing to know about this new Merck drug is that it's a synthetic estrogen (estriol), despite Merck's description of it as a 'natural estrogen hormone.'
From the European Medicines Agency's Scientific Discussion of Incurin:
Estriol is produced from estrone in a multi-step synthesis. Only the last step is described, consisting of a reduction with sodium borohydride in methanol. Estriol is purified with charcoal in methanol and crystallization from methanol.
That just sounds all kinds of 'natural,' doesn't it?
Synthetic estrogens are compounds created in a laboratory that mimic the activity of estrogen, but differ in structure from natural estrogens. When the structure of a naturally-occurring chemical is meddled with, it can set the stage for side effects ranging from the most minor to the most catastrophic.
Another reason we know Incurin is a synthetic hormone is because Merck (like all drug companies) can't patent a natural substance. Only synthetics can be patented, and patented drugs create massive profit opportunities for pharmaceutical manufacturers.
As I'm sure you're aware, synthetic estrogens have been linked to a wide range of serious health problems in women, including cardiovascular events like strokes and heart attacks, and breast as well as other types of cancer.
The side effects of Incurin noted in spayed female dogs to date include:
- Swollen vulva
- Vaginal discharge
- Renewed/increased attractiveness to males
- Increase in size of mammary tissue
- Rarely: GI disturbance, vaginal bleeding and hair loss
How the Drug Works
Estriol is produced naturally by the ovaries of animals. When the ovaries are removed during spaying, the drop in estrogen production can cause weakening of the urethral sphincter, which contains estrogen receptors. The urethral sphincter is the muscle that helps the body either contain or expel urine.
This condition is called Urethral Sphincter Mechanism Incompetence (USMI or simply SMI), and the result is that a spayed female dog may occasionally or routinely leak urine because the sphincter muscle can no longer perform its job effectively.
Replacing estriol, one of the three primary types of estrogens produced by the ovaries, can help tighten the urethral sphincter. This can return partial or complete control over urination, which reduces or eliminates the unconscious dribbling problem.
Estriol is a shorter acting estrogen than other forms. It is therefore thought the side effects, such as bone marrow suppression, seen in dogs taking other types of estrogen replacement are not a concern with estriol replacement. I assume this is the reason Merck uses a synthetic estriol in Incurin instead of, for example, synthetic estradiol.
Other potentially toxic pharmaceuticals commonly prescribed for canine USMI include:
- Phenylpropanolamine or PPA (norephedrine and norpseudoephedrine). This drug is of the amphetamine chemical class and in humans is used as an anorectic agent, a decongestant and a stimulant. PPA has been removed from the human market. In veterinary medicine the trade names for the drug are Propalin and Proin. It is used to treat urinary incontinence in both female and male dogs by increasing the tone of the urethral sphincter.
- Diethylstilbestrol or DES. This is a synthetic estrogen and is no longer a common choice for treatment of USMI because of its link to bone marrow suppression. It has been discontinued in its original form as a veterinary drug, however, despite its potential for serious side effects, some vets still have it made for their patients through compounding pharmacies.
Needless to say, all drugs carry the potential for side effects – sometimes very serious side effects.
Safe, Natural Help for Your Dog's Urinary Incontinence
I want to mention again that it's extremely important to have your vet determine the source of your pet's dribbling problem. The cause will dictate what type of treatment is required. In many cases I find underlying crystalluria or cystitis as a root cause of dribbling in pets.
If your dog is definitively diagnosed with hormone-related urinary incontinence, I urge you to try treating the problem naturally in collaboration with a holistic veterinarian.
I've personally had good success treating cases of hormone-induced urinary incontinence with a drug-free approach which can include:
- Glandular therapy supplements (Standard Process Symplex M or F)
- Herbal remedies (including Cornsilk)
- Non-synthetic hormone replacement therapy (plant-derived hormones)
- Homeopathic remedies
Suggestions for interim measures during treatment, or if your dog's incontinence can't be fully resolved:
- Take your leaky, furry friend for more frequent walks to encourage more frequent normal urination – this can help cut back on the amount of urine she has available to leak. It's generally a really bad idea to restrict your dog's water consumption to cut down on dribbling. If you're even tempted, please consult with your holistic vet first.
- Pile old, clean towels or blankets where your dog sleeps/dribbles, or consider purchasing doggy pee pads to put under her bedding to absorb moisture.
- Fit your pooch with dog diapers or bloomers/panties with absorbent pads. Baby disposable diapers can also work if you cut a hole for the tail. Make sure to remove or change these frequently, since urine is caustic to your dog's skin.
- Infections in dogs with urinary incontinence are very common, so make sure to constantly monitor the situation and provide proper hygiene (daily sponge baths) to your pet to prevent skin inflammation and infection.