Urinary Incontinence (Urethral Incontinence) in Dogs

What is urinary incontinence?

Urinary or urethral incontinence (UI) is the loss of control of urination. It is usually observed as involuntary urine leakage.

What are the clinical signs of urinary incontinence?

The most common clinical sign is pooling or spotting of urine under your dog when she is sleeping or relaxed. 

Many dog owners find wet spots on the bedding or floor where their dog has recently been laying down or sleeping. 

Occasionally, owners will notice their dog dribbling urine while walking or after urinating. In many instances, the dog seems unaware of what is happening. 

It is estimated that urinary incontinence may affect over 20% of all spayed female dogs and up to 30% of large-breed dogs. Urinary incontinence is most common in middle-aged to senior, medium to large-breed female dogs, although any dog may be affected.

What causes urinary incontinence?

There are several potential causes of urinary incontinence:

• Neurological causes, including spinal injuries, disruption of the nerves controlling the bladder, and brain diseases or lesions.
• Bladder storage dysfunction, including bladder hypercontractility (frequent contractions of the bladder) resulting in small amounts of urine leakage.
• Urinary tract infections, bladder tumors, or any condition that compresses the bladder from the outside.
• Urethral disorders in which the muscles that close the urethra fail to tightly contract and urine leakage occurs. This is one of the more common causes and is often associated with hormone responsive urinary incontinence, urinary tract infection or inflammation, prostatic disease in male dogs, and vestibulovaginal anomaly (abnormal reproductive anatomy) in females.
• Anatomic abnormalities such as a congenital defect, an injury, or a surgery that has caused damage or altered the normal bladder function. These abnormalities may include ectopic ureters (when the tube that carries urine from the kidney to the bladder is not in the correct anatomical location due to a birth defect), urethral hypoplasia (underdevelopment of the urethra), and conformational abnormalities in the vulva or around the vulva.
• Urine retention, in which a dog will not urinate due to stress, fear, or behavioral abnormality, and urine leakage occurs when the pressure inside the bladder exceeds their ability to hold their urine.
• Mixed urinary incontinence, which is the combination of multiple factors affecting normal urination. Combinations of urethral and bladder storage dysfunction and anatomic and functional disorders are most likely to occur.

How is urinary incontinence diagnosed?

Urinary incontinence is diagnosed based on clinical signs, medical history, blood tests, and urine tests. Bladder X-rays and ultrasounds are often performed to search for bladder stones or other abnormalities affecting urine storage and outflow.

Neurological tests, such as examination of the anal and tail tone, testing for sensation around the anus and vulva, and various spinal reflexes will be performed if a neurological disorder is suspected.

Passing a urinary catheter may be required if urine retention is observed. This determines if there is an obstruction or other urethral abnormality present.

Cystoscopy (a camera inserted through the urethra into the bladder) may allow your veterinarian to see an abnormality within these structures. In certain cases, specialized testing is performed, such as measuring the pressure within the bladder.

How is urethral incontinence treated?

Treatment is based on your pet’s specific diagnosis. Medications that increase urethral sphincter tone such as phenylpropanolamine (PPA), or hormone replacements such as estrogen or diethylstilbestrol (DES), are commonly used alone and in combination. Many dogs that respond poorly to PPA alone will benefit from a combination of PPA and DES. Approximately 70% of all cases respond well to medical therapy alone. Gonadotropin-Releasing Hormone (GnRH) may be considered in severe or refractory (failure to respond) cases. Imipramine, an anti-anxiety medication, may also be tried to relax the muscle tone in the bladder so that it can hold more urine.

With long-term usage, the patient's blood and urine should be periodically tested to ensure that there are no unexpected side effects. Your veterinarian will prescribe the best treatment for your pet's individual needs.

New research has focused on collagen injections to improve urethral closure. This surgical solution holds promise and should be discussed with your veterinarian to determine if any of the surgical specialists in your area perform this procedure. There are also several other surgical options (colposuspension and cystourethropexy) available for chronic incontinence, but these are usually performed by a specialist surgeon. In addition, there is ongoing research into the use of botulinum toxin and stem cell therapy for this condition.

What is the prognosis for urinary incontinence?

While the prognosis is determined by the specific cause, in general the prognosis is good. Control of urine leakage will vary from dog to dog, but most dogs can be managed successfully with medication, close monitoring, and lifestyle changes such as more frequent trips outside to urinate.