Does your dog awake from her sleep in a puddle of urine? Does she dribble urine when she stands up or is walking about? If so, she has involuntary urine leakage, known as urinary incontinence. Not only can this be bothersome and even embarrassing (dare I anthropomorphize) for the dog, it is truly a huge cleanup nightmare for the humans who live with a leaky dog. Urinary incontinence often results in frustrated attempts to use diapers, many loads of laundry, and irrational reprimands for the poor dog who has no control over the situation. Worst-case scenario, the dog who normally sleeps beside her master’s bed, is banished to the backyard.
The good news is, for most dogs, the leaking can be stopped or markedly diminished with appropriate therapy. The cause of the incontinence must first be established with appropriate diagnostic testing performed by a veterinarian.
When urine travels from the bladder (its holding reservoir) to the outside world it passes through a rather narrow tubular channel called the urethra. A muscular sphincter is present right at the point where the urethra connects with the bladder. It is this urethral sphincter that prevents urine leakage by remaining tightly closed. When the brain sends a signal that it is time to urinate, the bladder contracts at the same time the sphincter relaxes thus allowing urine to flow.
Hormone responsive urinary incontinence
Far and away the most common cause of canine incontinence is referred to as “hormone-responsive incontinence” or “acquired urinary incontinence.” It is a disease of neutered dogs- most commonly middle aged and older females, but occasionally occurs in males and younger females. Various studies report an incontinence incidence rate of 5-20% in spayed female dogs. There is evidence that neutering before three months of age substantially increases the risk of future incontinence.
Other factors that may be associated with increased risk for hormone responsive urinary incontinence include:
- Breed: Old English Sheepdogs, Doberman Pinchers, German Shepherds, Boxers, Weimaraners, Rottweilers, and Irish Setters are at increased risk.
- Size: Large and giant breeds have increased risk and small breed dogs have decreased risk.
- Tail docking: This surgical procedure performed on puppies of certain breeds is suspected to increase the risk of incontinence.
The diagnosis of hormone responsive urinary incontinence is made based on ruling out other potential causes and/or response to medication. Most dogs with this form of incontinence respond favorably to medication. The standard two that are tried alone or in combination are diethylstilbestrol (an estrogen product) and phenylpropanolamine (PPA). For dogs that are non-responsive to medication, treatment options include collagen injections or placement of a constricting ring at the site of the urethral sphincter.
Incontinence caused by increased thirst
Dogs who drink more water produce more urine. This translates into a bladder that becomes maximally distended, particularly during the night when a dog spends many hours in a state of sound sleep. This bladder distention can override the urethral sphincter, resulting in urine leakage. The key here is to hone in on the cause of the increased thirst. Correct this issue and the urine leakage typically resolves. Common causes of increased thirst include kidney disease, liver disease, urinary tract infection, and hormonal imbalances including diabetes mellitus, diabetes insipidus, Cushing’s disease, and Addison’s disease. Increased thirst can also be caused by some medications (diuretics, corticosteroids, anti seizure medications) and changes in diet.
Urethral sphincter abnormalities
Defects at the level of the urethral sphincter can interfere with its normal function. Such abnormalities can include bladder/urethral stones, prostate gland disease, tumors, and inflammation caused by infection. Resolution of the incontinence is dependent on successful treatment of the underlying disease.
Normal urine retention and voiding is dependent on a complex set of neurological signals involving the brain, spinal cord, and nerves leading to the bladder and urethral sphincter. Disease within this circuitry can result in urinary incontinence, typically accompanied by other neurological symptoms such as hind leg disuse or weakness and an inability to pass bowel movements normally. Therapy is dependent on the underlying neurological disease.
The most common cause of urinary incontinence in puppies is a birth defect called an ectopic ureter. Ureters are the narrow conduits that transport urine from the kidneys to the bladder. The term “ectopic” means in an abnormal place or position. An ectopic ureter transports and empties urine into the urethra rather than the bladder. The diagnosis of this plumbing defect is made visually either by passing an endoscope (a telescope-like device) into the urethra and bladder, or by performing an imaging study (CT scan X-rays) following the administration of contrast material. Incontinence caused by ectopic ureters can often be corrected surgically or with laser therapy.