Introduction

• Lack of voluntary control over flow of urine.
• Needs to be differentiated from dysuria, polyuria, abnormal elimination behavior.
• Cause: neurogenic disease, anatomic abnormality, acquired urinary tract disease.
• Signs: urine soiling or wetting in house.
• Diagnosis: involuntary flow of urine.
• Treatment: increase urethral tone, surgical correction of cause.
• Prognosis: good if cause treated.
  Print off the owner factsheet Urinary incontinence Urinary incontinence to give to your client.

Pathogenesis

Etiology

• Upper motor neuron disease (spastic neuropathic bladder).
• Lower motor neuron disease.

• Ectopic ureter(s) Ureter: ectopic.
• Female pseudohermaphroditism.
• Patent urachus Persistent urachus.
• Ureterocele Ureterocoele.
• Urethral diverticulum.
• Urethral fistula.
• Vestibulovaginal stenosis.
• Pelvic bladder syndrome Pelvic bladder.

• Inflammatory Cystitis or infiltrative disease of bladder Bladder: neoplasia or urethra Urethra: neoplasia.
• Sphincter mechanism incompetence Urinary incontinence: urethral sphincter mechanism incompetence.
• Prostatic disease Prostate disease or surgery.
• Complication of perineal urethrostomy Urethrostomy.
• Intermittent or partial urethral obstruction (paradoxical incontinence).

Predisposing factors

• Breed.
• Ovariohysterectomy.
• Obesity.
• Old age.
• Tail docking.
• Intrapelvic position of bladder.

Pathophysiology

• Normal urethral function is a combination of normal urethral elasticity, a normal smooth muscle in the proximal urethra, normal skeletal muscle further distally and an intra-abdominal bladder neck (increased intra-abdominal pressure is transmitted to the proximal urethral and the urine remains in the bladder).

• Structural abnormalitycausing (partial) obstruction, such as prostatic disease, inflammatory or infiltrative disease, urethral plug, urolith, neoplasia, stricture, polyp or a periurethral mass → incontinence when intravesical pressure exceeds urethra pressure → increased residual urine volume (>0.5 ml/kg).
• Functional abnormality(reflex dyssynergia): sympathetic or somatic neurological abnormality → inability of urethra to relax → incontinence when intravesical pressure exceeeds urethral pressure.

• Acquired urethral sphincter mechanism incompetence.
• Congenital urethral sphincter mechanism incompetence.
• Prostatic disease or surgery.
• Complication of perineal urethrostomy.
• Inflammatory or infiltrative disease of the urethra.
• Lower motor neuron disease (L1-L4 sympathetic innervation of smooth muscle in proximal urethra; L7-S3 innervation of urethral skeletal muscle in distal half of urethral in females and post-prostatic urethra in male dogs).
• Cauda equina syndrome Cauda equina neuritis.
• Dysautonomia Dysautonomia.

Timecourse

• Days to weeks before presentation.
• In some cases months.

Diagnosis

Treatment

Prevention

Outcomes