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Urinary Incontinence in Dogs
Treatment of Urinary Incontinence in Dogs
It may not be a "dinner party" topic of conversation, but as some of our Greys are getting a bit longer in the tooth, the subject of urinary incontinence comes up from time to time.
Urinary incontinence can be a result of a number of factors:
• hormonal - eg. oestrogen deficiency
• neurological - eg intervertebral disc disease, degenerative myelopathy
• anatomical - eg congenital ectopic ureters, or
• pathological – eg. urinary tract infections, bladder stones or tumours, prostatic disease in males or kidney disease
Incontinence is an involuntary leakage of urine and should not be confused with inappropriate urination for behavioural reasons (poor house training, marking territory, submissive urination due to fear, etc)
All dogs with a recent history of incontinence or loss of house training should be given a thorough physical examination by their veterinarian, to exclude non urinary tract disease. This examination should also include collection of a fresh urine sample for urinalysis +/- bacterial culture.
Urethral sphincter mechanism incompetence (USMI) is the most common cause of urinary incontinence in middle aged to older dogs. It is reported more commonly in medium to large breeds and is much more frequent in females than in males. Causes are multifactorial – hormone imbalances, genetics, obesity, age related changes in urethral musculature etc. The most commonly observed symptom is leaking urine while asleep. It can occur daily or be episodic (eg. after hard exercise) and may be mild to severe.
Although desexing of bitches (ovariectomy or ovariohysterectomy) has been incriminated as a cause of USMI, the vast majority of desexed bitches do NOT develop urinary incontinence (incidence reported at approximately 20%). In those that do, incontinence can occur immediately or up to 10 years after desexing. Scientific studies regarding the optimal age at desexing are contradictory. Oestrogen deficiency is not likely to be the sole cause, as plasma oestrogen concentrations are similar between continent entire bitches and incontinent desexed bitches. Also, oestrogen therapy does not resolve all cases of USMI.
Medical management of USMI can involve several different drugs that all act to stimulate receptors in the urethral muscle & increase urethral sphincter tone:
• Diethylstilboestrol (Stilboestrol ®) – a synthetic form of oestrogen. Used to be commonly used in tablet form (starting off daily until appropriate response is seen then gradually tapering off to twice weekly or weekly administration). Cheap drug & still used by some vets, but can cause bone marrow suppression. Safer drugs now available.
• Oestriol (Incurin ®)
• Pseudoephedrine (eg. Sudafed ®) – works well, but increasing more difficult to obtain over the counter at pharmacies due to its frequent use in elicit drug (amphetamine) production
• Phenylpropanolamine (eg. Propalin syrup ®) Administered two or three times daily – can be squirted into the meal. This drug was previously used in humans but was withdrawn due to high blood pressure problems. Side effects in dogs may include restlessness, anxiety and rapid heart rate (tachycardia). Most commonly prescribed drug for urinary incontinence.