24 | How to give great care to your dogs with urinary incontinence

PodcastUrinary
Written By Laura Jones

Incontinence is a really common urinary disorder - and it’s not just our older dogs who are affected by it.

 

It’s seen commonly in younger patients, too, and nurses are often heavily involved in their diagnostics, treatment, and ongoing care.

If you’ve ever thought that managing these cases is as simple as ‘dispense Propalin, and then discharge’, this episode is for you. 

We’ll look at what commonly causes urinary incontinence in dogs, some of the more weird and wonderful treatments we can use to manage urinary incontinence, as well as the nursing skills these patients benefit from.

But before we get into that, let’s start by looking at what urinary incontinence actually is and what causes urinary incontinence in dogs…

So, what is urinary incontinence, and what causes it? 

Urinary incontinence is defined as the involuntary passage of urine. Normally, urine is passively stored within the bladder and then passed consciously. This process requires coordination of the urinary bladder and the urethral sphincters. 

Urination begins with a storage phase, where the bladder relaxes and slowly fills, whilst the urethra remains closed. This is followed by a voiding phase - where the bladder contracts and the urethra relaxes.



Several urinary disorders can cause incontinence, including urinary tract infections, urinary calculi, urinary retention, bladder dysfunction, anatomical abnormalities, bladder shape and size, and neurological disorders.

Generally things like anatomical abnormalities, and urethral sphincter mechanism incompetence affect the storage phase, whereas things like urinary retention, obstruction, and overflow incontinence affect the voiding phase.

In today’s episode, we’ll focus on the main causes of incontinence in dogs: urinary sphincter mechanism incompetence (USMI) and ectopic ureters.

Let’s start by looking at USMI

USMI accounts for about 80% of canine urinary incontinence cases, is thought to affect 20% of all neutered female dogs, and 30% of neutered female dogs weighing over 20kg. It’s reported far less commonly in male dogs and in entire dogs of both sexes.

It can be either congenital or acquired. Congenital disease is less common and is associated with poor development of the urethral sphincter muscle. Most USMI cases are acquired and develop within 3-4 years of neutering, though it may not become a significant problem until later in life. Often, in senior patients, it is exacerbated by concurrent diseases causing PUPD, such as chronic kidney disease or Cushing’s disease.

Several breed predispositions exist. It tends to be larger breeds, including Old English Sheepdogs, Dobermans, Boxers, German Shepherds, Rottweilers and Weimeraners who are most affected. Studies suggest that neutering can increase the risk of USMI developing in dogs with a projected adult body weight of over 15kg.

So, what causes USMI?

Even though we have established many risk factors for USMI, the exact cause remains unknown. It’s likely to be multifactorial and include changes in the communication between the pituitary gland and reproductive organs, the anatomical structure of the urinary tract itself, and the structure and characteristics of the supporting structures around the lower urinary tract.

The position of the bladder, vascular tone, and the strength of the pelvic supporting structures are all important factors that help keep the urethra closed. If one of these is dysfunctional, it can contribute to USMI.

Some studies have also demonstrated that hormonal changes after neutering (declining oestrogen levels and increasing LH and GnRH levels), as well as a reduction in the number and sensitivity of alpha-1 receptors in the urethra, can affect smooth muscle contractility in the lower urinary tract. Hormonal changes also decrease the vasculature within the urethra and its surrounding structures, and given that urethral vasculature accounts for about 30% of urethral sphincter tone, this can cause significant urethral weakness.

Other studies have suggested that collagen content is altered in female dogs with USMI. Though further studies are needed to investigate this, collagen treatment is being performed more and more commonly in dogs with this condition—more on that later.

Lastly, we need to talk about bladder position. Normally, the pressure within the abdomen transmits to the bladder and proximal urethra. This equalises the pressure between the bladder and urethra, preventing urine leakage. In dogs with an abnormally caudal bladder—known as an intrapelvic bladder—any abdominal pressure increases (for example, when the patient barks, coughs, or moves), increasing the pressure on the bladder, and causing urine leakage.

What signs do we see in USMI patients?

Clients often report puddles of urine in areas where the patient rests or sleeps. The volume of urine passed will vary, and it can be anything from a few drops to a large puddle. 

Unlike other causes of urinary incontinence, patients with USMI will often not show any signs when they are awake or moving around. 

The urine passed is normal, i.e. not haemorrhagic and without a strong odour.

These patients are usually systemically well (unless they have a concurrent disease that has made the patient’s urination more obvious - like renal disease), and often, the only abnormality on examination is evidence of urine soaking or scalding around the vulva.

What about ectopic ureters?

In a healthy patient, the ureters enter the bladder in a region near the bladder neck, known as the trigone. A ureter that opens into the bladder in any other location is considered ectopic.

Ectopic ureters are the most common cause of incontinence in young dogs, and these patients usually present to us between 12 weeks and 1 year old. The condition is noted far more commonly in female dogs, since males have a longer urethral sphincter which can prevent urine leakage.

What causes ectopic ureters?

Ectopic ureters are congenital and caused by developmental defects in utero. The ureters can open into the lower urinary tract in different locations, including in the urethra, the vagina, and even the uterus, and they can have multiple openings in their final location.

We classify ectopic ureters as either extra or intramural. Extramural ectopic ureters completely bypass the urinary bladder and directly enter in a more distal location. Intramural ectopic ureters are a little different. If you were to look at them on imaging, they’d appear to enter the bladder. But, instead of entering the bladder lumen, they enter the bladder wall and tunnel through it, popping out again to enter the urinary tract at a different location (usually the urethra).

Concurrent anatomical abnormalities of the urethra, vagina and vaginal vestibule are common, and intramural ectopic ureters can actually also cause USMI, because the tunnelling ectopic ureter often disrupts the urethral sphincter.

Which patients get ectopic ureters?

As we’ve said, it’s commonly a disorder of young female dogs, though we suspect it is underdiagnosed in males since they don’t get such obvious clinical signs. The condition is also reported in cats, but is incredibly rare.

Like USMI, several breed associations have been identified, including Siberian huskies, Labrador retrievers, West Highland white terriers, golden retrievers, Newfoundlands, English bulldogs and miniature and toy poodles.

What signs do we see in these patients?

Intermittent or continuous dribbling of urine is the most commonly reported clinical sign, with many clients using nappies to avoid leaking around the home. 

Unlike USMI, this incontinence occurs day or night, regardless of whether the patient is awake or asleep. And just like with USMI, physical examination is often normal, except for the perineal urine-soaking or scalding we see in most incontinent patients.

So you’ve got an incontinent dog. What next?

To determine what’s causing your patient’s urinary incontinence, the first thing we need to do is collect a really detailed clinical history. We can start narrowing down our differential diagnoses by figuring out when the incontinence happens, what behaviour is displayed when consciously urinating, and what the urine looks like.

Questions to ask include:

  • How long the incontinence has been present for

  • How much is urine is passed, how often, and if the incontinence occurs at specific times (eg overnight only)

  • If the patient is neutered, and when they were neutered

  • If the patient has any dysuria, stranguria, haematuria or pollakiuria

  • If the patient has a history of lower urinary tract disease

  • If the patient has any other clinical signs, such as PUPD, vaginal discharge, neurological abnormalities (eg weakness or ataxia), or weight loss

Then we’ll move on to a full physical examination, followed by bloods, urine analysis, and diagnostic imaging. 

Let’s look at our examination first…

Physical examination should include an assessment of the perineal area for evidence of urine soaking or scalding, or evidence of overgrooming (eg saliva staining) in that area.

It should also include palpation of the urinary bladder, to assess size, tone, and position. If the bladder is palpable and obviously distended, it’s a good idea to see if it can be expressed easily. If you’re able to express it easily, this often indicates decreased contractility, but if it’s challenging to express, this can indicate a functional or physical obstruction.

A rectal examination should also be performed since this allows palpation of the urethra (as well as the prostate in male dogs). And lastly, a vaginal inspection should also be performed - though we often wait until the patient is sedated for their imaging for this, so that it’s a bit nicer for them!

Moving on to bloodwork and urine analysis

Bloods are often normal in these patients unless they have a concurrent disease - they are usually systemically well at presentation, and often, this is a disorder of younger-to-middle-aged dogs. Most of the time, we’re performing these as routine bloods, prior to sedation or anaesthesia for imaging.

Urine analysis is a vital diagnostic test in any patient with urinary incontinence. Minimum assessment should include a USG, chemistry strip and sediment examination; ideally, a culture and sensitivity should also be performed, since we know that UTIs are common in incontinent patients. Aside from signs of infection, if one is present, urine analysis is typically normal.

And then there’s imaging

Advanced urinary imaging studies are often performed in patients with incontinence, and they can—and should—be performed by veterinary nurses and technicians. 

Our goal with imaging is to rule out other causes of urinary incontinence, such as urinary calculi or a bladder or urethral mass, as we discussed in episode 23. Common techniques include both plain and contrast-enhanced radiography, ultrasound, and excretory urography.

Patients should be fasted for at least 12 hours and have an enema performed before their imaging, since faeces in the colon can impact visualisation of the lower urinary tract. This is generally performed whilst the patient is anaesthetised, to minimise discomfort and stress in hospital.

Double-contrast pneumocystograms - where the bladder is both inflated and filled with contrast medium, and retrograde urethrocystograms - where contrast is inserted up the urethra and into the urinary bladder - can highlight abnormalities such as an intrapelvic bladder, stones, and strictures.

Intravenous urography is commonly performed to diagnose ectopic ureters, and can be performed by nurses and technicians. This procedure involves administering intravenous contrast medium, and then performing carefully-timed, sequential CT scans of the urinary tract, to ‘catch’ the contrast exiting the ureters. We can then see the location of these ureters, and where exactly they are entering the lower urinary tract.

Ultrasonography is another common diagnostic tool in our incontinent patients. In larger dogs, we may be able to visualise the ectopic ureters on ultrasound. Aside from this, it also allows us to measure the bladder wall thickness, and identify any stones or masses. Nurses can acquire images, too - we just can’t diagnose based on them.

What about endoscopy?

Cystoscopy is another useful tool in investigating incontinent patients. It allows us to visualise the vagina, urethra, bladder and ureteral entrances and collect guided samples for histopathology and culture where needed.

It’s less invasive than surgical assessment and sampling, more comfortable for the patient, and allows us to perform some minimally invasive interventional treatments, too—but more on those in a second.

One last diagnostic to mention…

Urethral pressure testing is also described in patients with USMI. However, it’s a technically challenging procedure that requires specialist equipment and is not commonly performed. Instead, we tend to make a USMI diagnosis based on signalment, history, examination findings, and the urine analysis and imaging we’ve already mentioned.

How do we treat urinary incontinence?

The treatment options depend on what’s causing our patient’s incontinence.

Let’s start with USMI patients…

Treatment for USMI is usually achieved medically.

The drugs used are normally alpha-adrenergic agonists, such as phenylpropanolamine (propalin), ephedrine, or pseudoephedrine. These work on the receptors in the urethral sphincter, stimulating them and increasing urethral sphincter tone.

Propalin is effective in up to 90% of dogs with USMI.

Oestrogens are also commonly used in the treatment of USMI because they can increase urethral sphincter closure pressure and the responsiveness of alpha-1 receptors. However, unlike alpha-adrenergic agonists, oestrogen treatment is only effective in around 50-65% of patients.

Another treatment performed increasingly commonly is cystoscopic collagen injection. Under endoscopic guidance, collagen is injected into the tissue around the urethra. This narrows the lumen, allowing the urethral sphincter to close more effectively. Repeated injections are required, but improvement is seen in 75-93% of dogs.

And what about ectopic ureters?

Ectopic ureters are treated surgically or endoscopically wherever possible. 

Extramural ectopic ureters require surgical correction. Here, the ureter is dissected away from its abnormal entrance point and relocated to the bladder.

Intramural ectopic ureters now benefit from minimally invasive techniques. Cystoscopy-guided laser ablation is performed increasingly commonly in these patients. A laser fibre is inserted through the endoscope, and the tissue dividing the ectopic ureter from the urethra and urinary bladder is ablated.

However, regardless of how we treat an ectopic ureter, these patients can still develop USMI as a result and will require ongoing medical management for that if their incontinence persists.

What nursing care do these patients need?

These patients are not usually hospitalised for long, since they are systemically well on presentation. Most of our nursing skills are in helping with the diagnosis and treatment of the disease, as well as postoperative care.

The main consideration for these patients is cleanliness. They often present with severe perivulval scalding, requiring intensive checking, bathing, application of barrier cream, and preventing patient interference which compounds the dermatitis and redness often present.

Though this seems like a minor nursing skill, it makes a huge difference to these often very uncomfortable patients, and can be required hourly in severe cases - so is time intensive!

Monitoring the patient’s urination is vital in the hospital. Regular toileting opportunities should be provided, and the patient’s urination behaviour should be observed. Any abnormalities, like straining, changes in posture, or haematuria must be noted.

Regular bladder palpation should also be performed to ensure the patient does not have overflow incontinence if they have a voiding disorder.

Assisting with cystoscopy is another important nursing consideration. The veterinary nurse plays a huge role in endoscopy support - we’re not just there to anaesthetise these patients! Proper aseptic handling and management of the equipment, alongside patient preparation, emptying and refilling the bladder to allow visualisation, and sample collection, are all vital skills for the medicine nurse.

And following the patient’s procedure, we need to pay close attention to their comfort levels alongside general nursing care.

So there you have it! The complete guide to managing patients with USMI and ectopic ureters. Both of these disorders are common causes of incontinence in female dogs, with USMI being seen in older patients and ectopic ureters typically reported in puppies. Regardless of the cause, we can use many nursing skills with these patients, such as advanced contrast imaging studies and assisting with cystoscopy. Most importantly, though, the importance of simple interventions, like keeping these patients clean and comfortable, cannot be overlooked.

Did you enjoy this episode? If so, I’d love to hear what you thought - screenshot it and tag me on Instagram (@vetinternalmedicinenursing) so I can give you a shout-out and share it with a colleague who’d find it helpful!

Thanks for learning with me this week, and I’ll see you next time!

References and Further Reading

Laura Jones
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