Urinary incontinence in dogs

Overview

Storage and emptying

The bladder wall muscle relaxes during filling. Urethral sphincters retain urine meanwhile. Normally the bladder muscle contracts during urination. The urethra simultaneously relaxes to allow outflow.

Storage disorders can allow normal outdoor streams despite leakage at other times. Emptying disorders leave residual urine after attempts. Overflow occurs when full-bladder pressure exceeds urethral closure pressure. It can appear immediately after attempted urination.

An inner sphincter consists of smooth muscle. The outer sphincter consists of striated muscle. Sufficient bladder wall stretch triggers the urination reflex.

Causes

Sphincter weakness and congenital causes

Sphincter mechanism incompetence is the most common cause in adult bitches. Weak closure can let urine through when pressure rises during rest. Dysfunction can also begin in puppies before spaying. Ectopic ureters are the most common cause under six months. Their openings lie further back than normal, such as in the urethra or vagina. Urine can then bypass the sphincter.

Other storage and emptying disorders

A lodged stone can obstruct the urethra. Urinary tumours can also block it. Functional outflow obstruction can leave the urethra excessively tight during urination. Weak bladder contractions can also impair emptying. Spinal cord disease can disrupt function. Cystitis can also cause involuntary leakage.

A short urethra can impair retention because adequate closure pressure extends over less distance. Bladder retroflexion behind the pelvis can obstruct flow with perineal hernia. A narrow preputial opening can collect urine that leaks afterwards.

Risk factors

English primary care records estimated prevalence of 3.14% in bitches. The male estimate was 0.94%. Spayed bitches had an odds ratio of 3.01 compared with entire bitches in UK records. Castration was not associated with male incontinence after other factors were considered. Older male age groups were more affected.

Irish Setters and Dobermanns are among predisposed female breeds. Male Bullmastiffs differed from crossbreeds. However, that estimate used only five affected males. Female weight at least equal to breed adult average was associated with increased likelihood.

Incontinence has been found in 11–20% of large spayed bitches. English records found over 15% in several susceptible female breeds, including Bearded Collies and Dalmatians. Functional urethral obstruction most commonly affects young or middle-aged large and giant-breed males.

Typical symptoms

Leakage timing and urination pattern help distinguish causes. Note when leakage occurs and whether outdoor urination produces a continuous stream.

• Sphincter weakness can wet bedding during rest.
• Puppies with ectopic ureters can dribble while moving too.
• Involuntary bladder contractions can increase frequency.
• Bladder dysfunction can cause dribbling immediately afterwards.
• Functional obstruction can weaken and interrupt the stream near the end.
• Cystitis can cause visible blood.

A previously house-trained dog making a puddle in a urination posture may have cystitis. Increased urine production can worsen sphincter incompetence signs.

Ectopic ureter leakage can begin only in adulthood, particularly in males. Back or limb pain can impair urination if the usual posture becomes difficult.

Complications and consequences

Incontinence can predispose to bacterial cystitis. Residual urine also increases risk. Ectopic ureters can accompany recurrent urinary infections. Overdistension can impair bladder contraction.

Complete obstruction can produce waste accumulation symptoms within 36–48 hours. Potassium can rise dangerously. High potassium can cause serious arrhythmias. Prolonged obstruction weakens bladder muscle contraction.

Untreated obstruction can rupture the bladder wall. Prolonged obstruction can also damage its nerve supply.

Diagnosis at the vet

Urination pattern, sampling and residual volume

The vet establishes whether leakage began in puppyhood or later. The stream can be assessed directly or on owner video. Bladder size can be palpated before and after urination. Neurological examination assesses gait, hind limb positioning responses and tail tone, for example. Urinalysis and bacterial culture form part of initial testing.

Ultrasound measures post-void residual urine. For accuracy, measurement occurs within 10 minutes. A normal volume can be 0.2–1.0 millilitres per kilogram of body weight. Above 3 millilitres per kilogram of body weight suggests inadequate emptying. At 1–3 millilitres per kilogram of body weight, other signs and history guide interpretation.

Compatible signs with normal examination can prompt a sphincter medication trial. Recurrence prompts culture for concurrent infection.

Males may need several urination opportunities before measurement to reflect emptying accurately. Ultrasound is preferred to catheter measurement because catheterisation can introduce infection.

Endoscopy and imaging

Cystoscopy examines the lower urinary tract for ectopic openings. Ultrasound or CT examines upper tracts for additional kidney or ureter changes. Abnormal bladder areas can be biopsied during endoscopy.

One university hospital in northern Europe performed 47 canine cystoscopies during 2006–2016. Persistent or recurrent signs prompted referral in 29 patients, or 62%. Another investigation measures bladder pressure changes during filling.

Ultrasound can miss an ectopic opening despite visible ureter changes.

Treatment

Medication for sphincter incompetence

Bitches can be treated with phenylpropanolamine or an oestrogen such as estriol. Phenylpropanolamine stimulates inner sphincter receptors to help maintain closure. Blood pressure should be measured before and during treatment because it can rise. Reduced appetite is a possible adverse effect. Oestrogen can cause vulval swelling.

Response to phenylpropanolamine is usually assessed over at least 28 days. Among 19 bitches with congenital incompetence, five, or 26%, achieved complete continence with initial medication. Recurrence also prompts assessment for new disease such as infection.

Structural treatment

Ectopic ureters running within the bladder wall can often be corrected by endoscopic laser. Those outside the wall require surgical relocation of the opening. Endoscopic treatment has restored continence without additional medication in 47–72% of dogs. Leakage can persist with concurrent sphincter incompetence. Mechanical obstruction requires rapid restoration of flow.

Supporting emptying

Medicines relaxing urethral smooth muscle treat functional obstruction. Reduced residual urine helps assess effectiveness. Some lodged stones can be removed endoscopically with a retrieval basket. Blood tests after unblocking can check electrolyte recovery.

Bulking treatment for difficult cases

Persistent sphincter incompetence despite medication can prompt consideration of urethral bulking after endoscopic assessment. Material supports the wall and helps closure. A surgically implanted artificial sphincter is another option.

A trial tested nanocellulose bulking in eight spayed bitches unresponsive to medication. All scored at least eight out of 10 for continence at one month. Median continence without other treatment after one procedure was eight months. Flattening of deposits may have accompanied recurrence during follow-up. Two dogs developed single bacterial cystitis episodes. One developed recurrent cystitis.

Prevention

A timing study compared spaying from three to under seven months with seven to 18 months. Later-spayed bitches had an odds ratio of 0.80 for diagnosis before age 8.5 years compared with earlier spaying. Another UK study found no association with age at spaying. Weight monitoring particularly matters in susceptible bitches because higher weight relative to breed average was associated with more diagnoses.

The timing comparison included 612 earlier- and 888 later-spayed bitches. It used records of operations already performed.

Important for dog owners

Record whether bedding became wet at rest or dribbling followed outdoor urination. Film posture and the stream outdoors. Report clearly increased drinking. Also mention faecal leakage or altered gait.

Monitor leakage consistently before and during treatment for comparison between visits. Record adverse effects such as appetite reduction after starting medication.

Frequently asked questions

Why is bedding wet despite normal outdoor urination?

Storage disorders can allow normal urination with resting leakage. This fits sphincter incompetence in adult bitches. Urine testing checks for concurrent infection. Blood or straining can accompany infection.

Is a puppy's constant dribbling a house-training problem?

Leakage during movement and rest fits an ectopic ureter. It may open into the urethra or, in females, vagina. Endoscopy can locate the opening. Ultrasound can assess kidneys and ureters during the same investigation.

Can urine leak when the bladder does not empty?

A full bladder can drip when its pressure exceeds closure pressure. Ultrasound measures residual volume after urination. Call an emergency clinic immediately for repeated straining without a stream.

Can males be incontinent?

It is less common than in females but also affects uncastrated males. An interrupted stream can indicate poor emptying. Residual volume measurement is particularly useful in male investigations.

Do bacteria in urine need antibiotics?

Positive cultures can occur without typical bacterial cystitis signs. Asymptomatic findings usually need no antibiotics. Pain or frequency matters when interpreting culture. Asymptomatic bacteria can resolve spontaneously.