Incontinence
Involuntary loss of urine (urinary incontinence) or feces (fecal incontinence). Urinary incontinence is more common and often results from urethral sphincter mechanism incompetence, particularly in spayed female dogs.
Incontinence is the involuntary loss of urine or feces — the dog leaks without awareness or voluntary control. It is distinct from house soiling (behavioral inappropriate elimination) and from urgency (the dog knows it needs to go but cannot reach the appropriate location in time).
Urinary Incontinence
Urethral Sphincter Mechanism Incompetence (USMI)
The most common cause of urinary incontinence in dogs, particularly in spayed females. The urethral sphincter loses tone and cannot maintain closure during rest, resulting in urine leakage — typically noticed as wet spots where the dog has been sleeping.
Risk factors include:
- Spay status: estrogen contributes to urethral sphincter tone. Spaying removes the primary estrogen source, and incontinence develops in approximately 5-20% of spayed females.
- Body weight: larger dogs are more commonly affected (some studies report incidence up to 30% in dogs over 20 kg)
- Breed predisposition: reported higher incidence in German Shepherds, Rottweilers, Weimaraners, Irish Setters, Doberman Pinschers, and Old English Sheepdogs
- Spay timing: some evidence suggests very early spaying (before first heat) may increase risk, though this remains debated
Other Causes of Urinary Incontinence
- Ectopic ureters: congenital condition where one or both ureters bypass the bladder and enter the urethra or vagina directly. Common in certain breeds (Siberian Husky, Golden Retriever, Labrador Retriever).
- Neurologic causes: spinal disorders, intervertebral disc disease, lumbosacral disease — damage to the nerves controlling the bladder and sphincter.
- Urinary tract infection: can cause urgency and leakage that mimics incontinence. Must be ruled out before diagnosing USMI.
- Detrusor instability: overactive bladder contracting involuntarily.
- Overflow incontinence: bladder overdistension from obstruction or neurologic dysfunction.
Treatment of Urinary Incontinence
- Phenylpropanolamine (PPA): alpha-adrenergic agonist that increases urethral sphincter tone. First-line treatment for USMI with response rates of 75-90%.
- Estrogen supplementation: estriol (Incurin) or diethylstilbestrol (DES) can improve sphincter tone in spayed females.
- Surgical options: urethral collagen injections, colposuspension, or hydraulic urethral occluder for refractory cases.
- Ectopic ureter correction: surgical reimplantation or laser ablation.
Fecal Incontinence
Less common than urinary incontinence. Causes include:
- Neurologic disease (lumbosacral stenosis, degenerative myelopathy)
- Anal sphincter damage (trauma, surgery)
- Severe colorectal disease
- Cognitive decline in senior dogs
Fecal incontinence is often more challenging to manage and typically signals significant underlying disease.
When to Investigate
Any new-onset incontinence warrants veterinary evaluation to identify the cause and rule out treatable conditions. Diagnostic workup typically includes urinalysis, urine culture, blood work, abdominal imaging (ultrasound or radiographs), and neurologic examination based on clinical suspicion.