Incontinence in dogs

Many of our patients suffer from urinary incontinence, particularly as they get older. For some dogs the problem can start even earlier in life, but we’d generally expect to see this problem from middle age onwards. Urinary incontinence can result from congenital abnormalities, urine retention, urine overflow and sphincter incompetence. In this article we look at the most common cause of incontinence, urethral sphincter incompetence (USI).

Posted: 12 August 2019

Incontinence in dogs

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Urethral Sphincter Incompetence

This problem can affect up to 1 in 5 neutered females (for neutered females weighing over 20kg, this increases to 1 in 3). It is less common in males and entire females.

In most dogs, the problem usually develops within a few years of neutering, though in some cases may not been seen until they are much older, when polyuria and polydipsia may exacerbate an underlying problem. Some breeds seem to be more frequently affected, such as the Old English sheepdog, Doberman Pinscher, Boxer, German Shepherd, and Weimaraner.

What causes USI?

The reasons for an animal developing USI are almost certainly multifactorial, and include;

  • Hormonal changes – a rise in luteinising hormone and gonadotropin-releasing hormone, as well as increases in their receptors in female animals secondary to the decline in oestrogen levels after neutering, have both been implicated.
  • Suspensory structures - the strength of supporting tissues in the pelvic region may affect smooth muscle contractility in the lower urinary tract.
  • Bladder position – dogs with a caudally positioned bladder will develop pressure changes resulting from movement, barking and coughing. An increase in abdominal pressure is transmitted to the bladder, resulting in a forced leakage. 

Making a diagnosis – clinical signs and evidence

A. Early signs – most owners notice

Owners may find a wet patch on the carpet, in the dog’s bed or perhaps even on the sofa. The wet area is often discovered after the pet has been sleeping for a while. We’ll occasionally find that a dog will dribble urine even after she has been out for a walk and passed normally. Look for some of these classic signs;

  • Unpleasant smell - a strong smell of urine, either on the dog or in their bedding
  • Scalding – check the skin for hair loss, inflammation and infection
  • Licking – most dogs with incontinence will be bothered by the urine leakage, and will spend more time licking around the vulva

B. Clinical investigation

It’s important to rule out any other causes of incontinence when investigating a suspected case of USI. The standard tests would include;

  • Blood tests – to confirm normal renal function and rule out a suspected infection, anaemia or electrolyte disturbance.
  • Urine analysis – check for blood, bacteria and bladder infections.
  • Ultrasound – check the kidneys, bladder and if feasible, the ureters, for any abnormalities.
  • Radiography – contrast studies are most valuable. A double contrast cystogram is useful for checking the position of the bladder neck, identifying bladder wall abnormalities or looking for evidence of bladder stones.
  • Intravenous urogram (IVU) – follow the flow of urine from kidneys into the ureters and bladder. If an ectopic ureter is present it will be seen.
  • Retrograde studies – this technique is used to examine the anatomy of the vagina and possibly reveal ectopic ureters not seen in the IVU.
  • Cystoscopy – useful in medium and large breed dogs to rule out ectopic ureters.

Treatment options – what’s available?

Many dogs with USI will respond to medical treatment. Whilst most will either become continent or at least significantly improved, there will always be some that don’t show any improvement, so make sure you set realistic expectations. The standard approach in the UK is to use phenylpropanolamine, though this is not suitable for all cases. The treatment is usually given daily and is generally considered safe. A minority of dogs may show some behavioural changes, in which case they could be offered an oestrogen analogue instead.

1. Phenylpropanolamine – see Propalin and Urilin. Phenylpropanolamine should be used with caution in patients with heart disease, pre-existing high blood pressure, glaucoma, hyperthyroidism and diabetes mellitus as it can cause hypertension and tachycardia.

2. Surgery – this is often offered for those dogs where medical treatment is unsuccessful. There are a number of techniques available, all of which have very similar success rates, such as;

  • Urethropexy – the urethra is surgically fixed in a position which is designed to improve urine leakage
  • Colposuspension - the vagina, urethra and bladder neck are surgically held in a position designed to improve continence
  • Collagen injections – these are placed into the bladder neck. These injections may need to be repeated every couple of years.

The prognosis following surgery is similar with all these techniques. Around 80% of surgical cases are successful, though some do require supplemental medication.

Are there other causes of incontinence?

There can be many other causes, including bladder infections, bladder stones and in more serious cases bladder tumours. A fresh urine sample will be required to check for signs of infection and abnormalities.

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