Oh, no! My (spayed) dog has sprung a leak!

By Patty Khuly, DVM on Oct. 4, 2009

Among the most annoying, chronic problems in dogs occurs when they occasionally spring a leak (of urine, that is).

But I’m not referring to the stand-up-and-aim variety ubiquitous among unneutered males, nor to the frequent messes made by the untrained. This is the kind of leak that occurs most often in spayed female dogs. It typically happens while they’re sleeping or resting. And punishment is contraindicated, as they have no idea they’ve done it –– and it's certainly NOT their fault.

Primary urinary sphincter mechanism incontinence is the diagnosis most often applied to this condition. It is by far the most common kind of incontinence in dogs and seems to result from a weakness of the muscles in the urethra near the bladder (the urethra is the tube that connects the bladder to the outside world). Large breed, older, overweight, spayed dogs are overrepresented among the afflicted, but any dog can acquire this problem.

Among spayed dogs, studies show that changes in estrogen and progesterone levels affect the urinary sphincter mechanism at the level of the smooth muscle in the urethra. The smooth muscle works as part of the involuntary nervous system. Hence, no measure of training could override this incontinence in a sleeping dog.

Dribbling while walking or lying down, wet spots on bedding or sleeping areas, and frequent licking of irritated skin in contact with urine are some of the most common signs of this disorder.

Many of these dogs also have urinary tract infections or other problems with their urinary tracts. Commonly, these issues are the result of the primary incontinence. Consider that a weak sphincter is likely to allow bacteria to travel into the bladder. Consider, also, that urine collecting on irritated skin is a great breeding ground for this bacteria. It’s no wonder many of these dogs are assumed to suffer from a simple UTI (urinary tract infection) or cystitis (a specific kind of UTI: a bladder infection).

All dogs with the symptoms listed above should be evaluated by a veterinarian. Urinalysis and bloodwork are basic diagnostic measures but some dogs will need X-rays, ultrasound, or culture and sensitivity (to determine the kind of bacteria present should they have an infection).

Veterinarians used to treat these presumed hormone-related urinary incontinence cases with supplemental hormone injections or pills. These have been found to have side effects so numerous that a newer treatment is now preferred. The drug phenylpropanolamine is now the leading choice. It is considered safe and extremely effective, but only serves to make the sphincter work more effectively in the short term. Therefore, the drug has to be administered for the dog’s entire life. Luckily, it comes in chewables.

At issue with this disorder is the near-certainty that sterilization is associated with it. Early spaying (six months or earlier) may be even more likely to cause it ... but we're not sure if timing has anything to do with it at all. Luckily, it's a relative few dogs out of every hundred that suffer it, leading us vets to continue to recommend the spay operation. Because incontinence is treatable, it's considered more important to mitigate the pet overpopulation and other diseases (like mammary tumors, which are preventable via female sterilization) by performing a spay early, rather than to recommend a later timing for the spay. Stay tuned as science sorts out the rest. 

Dr. Patty Khuly


Patty Khuly, DVM


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