Has your dog started urinating randomly in the house in the evenings? If the answer is yes, you are not alone in this stressful situation. Urinary incontinence is a common problem in dogs and there can be multiple causes, many of which can be treated or managed by your Vet. This article aims to explore the ins and outs of urinary incontinence in dogs.

Table of contents

A bit of physiology

So, let’s start with a brief bit about the physiology of urination. The control of urination is via a combination of both the voluntary and involuntary nervous system. To keep it simple, one part stimulates the bladder wall smooth muscle to contract, whilst the other part relaxes the bladder sphincter. When these mechanisms work together correctly, the timing and action of urination can be controlled. When the bladder lumen fills with urine, this urine is then voided via the urethra. 

What is urinary incontinence?

Urinary incontinence is the loss of voluntary control of urination, resulting in the passive leakage of urine. It more commonly occurs in older canines and mostly affects female dogs. Urinary incontinence is usually triggered by a medical condition and most dogs are unaware that they have voided urine at the time. For obvious reasons, dogs urinating in the house is undesirable and it is definitely more of a recognised issue nowadays because most dogs are living indoors.

What causes urinary incontinence?

There are a few problems and conditions which can lead to urinary incontinence. The following list will discuss some of these differentials (this list is not exhaustive):

Urethral sphincter mechanism incontinence (USMI)

Also referred to as ‘spay incontinence’, this is one of the reasons that female dogs more commonly experience urinary incontinence compared to males. There has been a reported prevalence of urinary incontinence between 5 and 20% of spayed females (Forsee et al, 2013). This is the most common cause of acquired urinary incontinence in dogs (Applegate et al, 2018). Dogs affected usually leak urine when they are lying down. Acquired USMI is quite often seen following spaying, it has been suggested that the reduction of hormones decreases the urethral tone.

Urinary tract infection (UTI) 

UTIs are common in dogs. Dogs with UTIs often feel the need to urinate more frequently and sometimes they can leak or dribble urine. In most cases, UTIs develop as a result of an ascending infection from the outside world, tracking up the urethra and into the bladder. Similar to USMI, UTIs are more likely to occur in females than in male dogs. The reasons are likely due to the longer and narrower urethra of the male dog, which makes it harder for bacteria to penetrate all the way to the bladder.

Urinary/bladder stones 

Bladder stones can develop in any dog and the clinical signs can include difficulty urinating, increased urination or inappropriately dribbling urine. Bladder stones are rock-like formations or minerals that form within the bladder, there may be multiple small stones present or one large stone.

Spinal injury 

A traumatic spinal cord injury could lead to urinary incontinence. This is due to the anatomical location of the nerves which innervate or stimulate the bladder. The pelvic parasympathetic nerves arise at the level of the spinal cord and therefore when there is injury to the spinal cord, these nerves are unable to signal properly. Therefore, in patients with spinal injury, urinary catheterisation is often used or medications are given to stimulate voiding of urine.

Anatomical/congenital abnormalities

Ectopic ureters are the most frequent anatomical cause of urinary incontinence (Holt and Moore, 1995). In this condition, the affected dog will have their ureter(s) enter the bladder in an abnormal location, urinary incontinence is usually noticed in early puppyhood. 

Tumours 

Sadly, neoplasia (cancers) of the urinary tract can lead to urinary incontinence. These tumours may arise from the bladder or the urethra. The most common type of bladder cancer in dogs is transitional cell carcinoma, an aggressive malignant tumour of the bladder and/or the urethra. This is most commonly seen in middle-aged to older dogs.

How is it managed?

To successfully treat urinary incontinence, the primary cause needs to be correctly identified, which is not always an easy task! Your Vet may suggest performing a variety of diagnostic tests including bloods, urinalysis and abdominal/urinary imaging.

Understandably, one thing pet owners are often most interested in is how it can be stopped or controlled. Most cases of USMI can be treated with medication, this is usually effective in 60-90% of cases. Uncomplicated UTIs are often treated with medication, usually a course of antibiotics and anti-inflammatories. Surgery is often indicated in more complex situations including bladder stones and ectopic ureters. 

Please contact your Vet for further advice if you notice any signs of urinary incontinence in your dog.

Conclusion

To conclude, urinary incontinence is a common issue seen in Veterinary practice of which depending on the cause several medical treatment options are available or surgery may be recommended. It certainly isn’t something that should be left unnoticed in any dog, young or old!

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