When a house pet develops urinary incontinence, many owners fear the worst. Assumptions that incontinence signifies senility or irreparable age related change may lead to delay in medical consultation, relegation of the pet to an outdoor life, or even euthanasia. In reality, urinary incontinence is usually one of easiest problems to solve so it is crucial that veterinary assistance be sought before an owner’s patience is completely worn and before any permanent decisions about the pet’s future become topical.
Causes of Incontinence
It is important to differentiate incontinence (involuntary urine leakage) from behavioral urinary issues (submissive urination), simple lack of housetraining, territorial marking of unneutered males or anxious cats, or the senile loss of house-training from canine cognitive dysfunction. Animals may urinate in the house voluntarily and this is different from incontinence. Watch your pet closely to be sure what you are seeing is really incontinence and if it is, the good news is that most cases are easily resolved with simple inexpensive medications.
There are several important causes of incontinence and most of these are ruled in or out with a urinalysis and urine culture. The urinalysis reveals cell types and biochemical elements in the patient’s urine while the culture isolates and bacteria growing in the urine. The bacterial species grown are identified and tested for their sensitivity towards different antibiotics, the end result being confirmation of the presence of infection and a list of appropriate antibiotics.
Most cases of incontinence are due to:
• Infection in the urinary tract (usually bladder infection)
• Excessive consumption of water
• Weak bladder sphincter (especially common in female dogs)
• Spinal cord disease
This is a common cause of urinary incontinence in young adult female dogs and geriatric cats. This condition is usually easily diagnosed by urine culture, though often signs of infection such as white blood cells or bacteria are actually visible in the urinalysis. A urine culture will confirm the infection, identify the organism, and list usually several antibiotics which will be effective. An antibiotic is selected based on expense, potential for side effects, and convenience of usage. After a short course (generally somewhere between one and three weeks) of medication, ideally a second urine culture is done to confirm that the infection has truly been cleared up. If a bladder infection is the cause of incontinence, most patients show improvement in their incontinence and comfort after only a few doses of antibiotics (but it is still important to finish the entire course so as to avoid recurrence).
Excessive Water Consumption
Some animals drink so much water that their bladders simply overflow too easily. While some owners have noticed that their pets seem to be drinking more than usual, our experience is that most owners are surprised when the urinalysis shows excessive water consumption. Dilute urine is obvious on the urinalysis through a measurement called “specific gravity” which compares the amount of dissolved biochemicals in the urine to that of pure water (which has no dissolved biochemicals). A urine specific gravity nearly the same as water, confirms excessive water consumption; blood tests may be indicated to go with the urine tests to determine the cause.
Causes of excessive water consumption include:
• Diabetes mellitus
• Cushing’s Syndrome
• Hyperthyroidism (cats)
• Bladder Infection (see above)
• Diabetes Insipidus
• Kidney failure
There are other causes as well but 90% are ruled in or out by a blood panel and urine culture.
Weak Bladder Sphincter
Aging, obesity, reduced sensitivity of neurologic receptors in the sphincter and possibly other factors all contribute to this condition which is especially common (up to one in five affected) in female dogs. Once other more serious conditions have been ruled out, the weak sphincter may be treated symptomatically with one of several medications.
It is not entirely clear how estrogens are helpful in this treatment. Originally, estrogens were given to post-menopausal women with urinary incontinence and the treatment was simply extrapolated to dogs. It is possible that estrogens are important in the maintenance of neuroreceptors in the bladder sphincter and without estrogens the receptors become unresponsive to the transmission of the “storage” message from higher neurologic centers. In dogs, DES (diethylstilbestrol) is the most common estrogen used, though it is now only available through compounding pharmacies. A higher dose is used to begin therapy and finally a maintenance dose of usually every few days is used to maintain continence. The main drawback to DES is its association of causing anemia in some patients. In male dogs, testosterones seem to be more effective than estrogens, possibly through action on the prostate which sits at the neck of the bladder and incorporates the sphincter.
A newer estrogen called estriol, sold under the brand name, Incurin, has shown a lot of promise in terms of being both more effective for treatment of female canine urinary incontinence, as well as significantly safer. Data and and anecdotal evidence at this time indicate minimal risk of anemia that DES has been associated with.
• Alpha-Adrenergic Agonists
These medications act by enhancing release of the neurotransmitter chemicals that act on the receptors of bladder sphincter. Effectively, they turn up the volume dial on the “hold it” message from the high neurologic areas. The usual medication for canine use is phenylpropanolamine, currently available in liquid and chewable tablets and is typically given two or three times daily. Ephedrine and pseudoephedrine, common decongestants, may also be used. Side effects can include irritability, appetite suppression (phenylpropanolamine was the active ingredient in many human diet pills until recently), and blood pressure changes. Most dogs (male and female alike) tolerate phenylpropanolamine uneventfully.
For especially resistant cases of incontinence, estrogens and alpha-adrenergic agonists can be used together.
Anticholinergic drugs are medications that work, not on the sphincter of the bladder, but on the rest of the bladder where urine is stored, relaxing the muscle fibers thus facilitating storage. A drug called Imipramine is an anti-anxiety medication commonly used in humans. It has anticholinergic properties and can be used in combination with phenylpropanolamine in the treatment of animal incontinence. Imipramine is not commonly used compared to the other two medication types which are extremely effective but it may provide another choice for the few patients who do not respond to traditional therapy.
Medication works for most patients with weak sphincters, but when medication fails there are some surgical options to consider: colposuspension and cystourethropexy.
Colposuspension, for females only, is the most commonly performed procedure. Here, the vagina (located just above the urethra as the dog stands) is tacked to the bottom of the belly wall entrapping and compressing the urethra. In one study of 60 female dogs receiving this surgery, 40% were cured of their incontinence and 42% were improved. In another study, 23 spayed female dogs with incontinence received colposuspension and 55% were cured at their 2 month recheck but only 14% were still cured at the 1 year recheck. This number jumped to 43% fully continent when medication was added back in. Another 43% were judged by their owners as greatly improved when medication was added back in. Over all owner satisfaction with surgery was 86% in this study.
Cystourethropexy is the modification that can be performed in males. Since there is no vagina to use, the ductus deferens are tacked down to compress the urethra. Fibers from the urethral muscles can also be tacked down (in either male or female patients).
Medications listed above are used in conjunction with surgery. Surgery alone improves approximately 50% of patients but often incontinence returns unless medication is also used.
Unusual Causes Of Incontinence
The list of causes of incontinence presented above is by no means exhaustive. While uncommon, other causes should not be entirely counted out. Some possible causes include:
• Ectopic ureter (instead of connecting to the urinary bladder, the ureter transporting urine from the kidney connects to the vagina or rectum so that there is no storage of urine. This condition is typically noted in a puppy that simply cannot be house-broken and leaks urine. The condition can be solved surgically.)
• Spinal damage especially in the lower lumbar area
• Infection higher in the urinary tract (kidney or ureter)
Your veterinarian is in the best position to determine if it is worthwhile to pursue a rare disease or not. Do not hesitate to ask your veterinarian questions regarding your pet’s incontinence, the treatments or procedures described above
Roger L. Welton, DVM
Founder and Chief Editor, Web-DVM.net
President, Maybeck Animal Hospital
Article updated 6/3/2014