Urinary incontinence is a fairly common problem in spayed female dogs as they age. Quite often, she will be unaware that she's leaking urine, though you may be very aware of it when it happens inside your home. The good news is that your veterinarian may be able to prescribe a medication to help.
While there are a variety of potential causes for urine leakage, incontinence in middle-aged or senior spayed female dogs is usually due to the lack of estrogen. This is known as hormonal incontinence.
This type of incontinence is due to the fact that estrogen strengthens the dog's muscles which control urination. When the hormone levels become lower with age, her muscles can no longer hold urine in the right place. As urine collects in the vestibule area, it can then leak out when she moves. This is why you'll often notice it when she gets up or lies down.
In most cases, urinary incontinence is the only problem, though sometimes a urinary tract infection is seen as well.
Traditionally, drugs containing phenylpropanolamine (PPA) have been used to increase the smooth muscle tone of the bladder and urethra to help control the flow of urine. This class of drugs is not hormone-based, however. PPA was used in human medications for colds and appetite suppression (weight loss) but has been removed from the human over-the-counter (OTC) market.
In 2011, the U.S. Food & Drug Administration (FDA) approved Incurin, the first hormone-based incontinence medication for dogs. This drug is a natural estrogen hormone and is labeled only for hormone-responsive incontinence in female dogs.
From the FDA:
Estrogens increase the resting muscle tone of the urethra in females and can be used to treat female dogs with urinary incontinence due to estrogen depletion.
In a placebo-controlled field study of 226 spayed female dogs, a greater percentage of dogs treated with Incurin were improved (fewer or no incontinence episodes) 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 of age and older.
The most common side effects associated with Incurin treatment included a loss of appetite, vomiting, excessive water drinking and swollen vulva.
The introduction of Incurin is a welcome change in the treatment of female dogs with urinary incontinence. It is the first medication that is dedicated to treating the root of the problem and restore estrogen levels to those similar to a younger, unspayed dog.
What You Can Do
If your spayed female dog has problems with urine leakage, such as a pool of urine left on her bed after sleeping, the first step is to see your vet. She will likely call for a urinalysis and bloodwork to rule out a urinary tract infection or other diseases such as diabetes or kidney disease.
If hormonal incontinence is diagnosed, your veterinarian can help determine the best treatment to help manage this condition for your dog. She may feel that Incurin is not a good option, but it is a viable choice for treatment.
U.S. Food & Drug Administration. FDA Approves First Drug to Treat Urinary Incontinence in Female Dogs. 2011.