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Urinary Incontinence

 (Involuntary Passage of Urine)

OVERVIEW

•  Loss of voluntary control of urination, usually observed as involuntary urine leakage while resting

Signalment/Description of Pet

Species

•  Dogs
•  Cats—rare

Breed Predilections

•  Medium- to large-breed dogs most often affected

Mean Age and Range

•  Most common in middle-aged to old, spayed female dogs; also observed in juvenile females and (rarely) cats or neutered male dogs

Predominant Sex

•  May affect more than 20% of spayed female dogs, especially large-breed dogs

Signs/Observed Changes in the Pet

•  Urine dribbling without the pet’s control
•  Wet hair coat on lower abdomen, area between rear legs and onto rear legs; inflammation of skin (known as “dermatitis”) in these areas; pet may lick affected areas
•  Evidence of urine wet spots or puddles in bedding, where pet was sleeping or sitting, other locations in house
•  May have signs of urinary tract infection (such as straining to urinate, blood in the urine, painful urination)
•  Urine scald (skin condition that looks like a burn due to the irritation of urine on the skin)
•  Inflammation of the skin and moist tissues of the vulva or the prepuce (around the penis)
•  Leakage may be worse after the pet drinks lots of water or exercises strenuously

Causes

Nervous-System Disorders

•  Disruption of nerves involved in storage of urine in the bladder or act of urination
•  Lesions of the sacral spinal cord, such as a birth defects; cauda equina syndrome, a group of disorders in which the lumbosacral vertebral canal is narrowed, resulting in pressure on the nerve roots as they leave the spinal cord; lumbosacral intervertebral disk disease; or traumatic fractures or dislocation can result in a flabby, overdistended urinary bladder; urine retention and overflow incontinence develop
•  Lesions in the brain may affect voluntary control of voiding, usually resulting in frequent, involuntary urination or in leakage of small volumes of urine

Urinary Bladder-Storage Disorders

•  Poor accommodation of urine during storage or urinary bladder overactivity (so-called “overactive bladder” or “detrusor instability”) leads to frequent leakage of small amounts of urine
•  Urinary tract infections; chronic inflammatory disorders, such as “chronic cystitis”; cancer involving the bladder; pressure on the bladder from masses or fat; and chronic partial obstruction of the urethra (the tube from the bladder to the outside, through which urine flows out of the body)
•  Underdevelopment of the bladder (known as “congenital urinary bladder hypoplasia”) may accompany other congenital (present at birth) developmental disorders of the urinary and reproductive tracts
•  The detrusor muscle acts to squeeze the bladder to expel urine; disorders of this muscle (known as “idiopathic detrusor instability”) has been associated with feline leukemia virus (FeLV) infection in cats and unknown causes in dogs

Urethral Disorders

•  The urethra is the tube from the bladder to the outside, through which urine flows out of the body
•  Intermittent urinary incontinence is observed if urethral closure provided by urethral smooth muscle, striated muscle, and connective tissue does not prevent leakage of urine during storage
•  Examples—underdevelopment of the bladder (congenital urinary bladder hypoplasia); acquired (develops during life/after birth) urethral incompetence (such as reproductive hormone–responsive urinary incontinence); urinary tract infection or inflammation; prostatic disease or prostatic surgery (male dogs)

Anatomic or Structural Disorders

•  Developmental or acquired anatomic abnormalities that divert urine from normal storage mechanisms or interfere with urinary bladder or urethral function
•  The ureters are the tubes from the kidneys to the bladder; during development, they may not attach to the bladder properly or may attach to reproductive organs instead; when this occurs, they are called “ectopic ureters” and one or both can terminate in the distal urethra, uterus, or vagina
•  Patent urachal remnants divert urine outflow to the umbilicus
•  Abnormalities of the vagina, bladder or urethra
•  Intrapelvic bladder neck location may contribute to urine leakage due to urethral incompetence (the inability of the urethra to prevent urine flow)
•  Conformation abnormalities of the vulva or tissues around the vulva may contribute to urine pooling and intermittent urine leakage

Urine Retention

•  Overflow observed when pressure within the bladder exceeds the ability of the sphincter and urethra to prevent urine flow

Mixed Urinary Incontinence

•  Mixed or multiple causes of urinary incontinence are observed in people and probably occur in dogs and cats; combinations of urethral and bladder-storage disorders and combinations of anatomic or structural and functional disorders are most likely

Risk Factors

•  Neutering is the main risk factor for urinary incontinence; however, many spayed female dogs do not develop incontinence
•  Early spay (surgical procedure is removal of ovaries and uterus; known as an “ovariohysterectomy”) in puppies less than 3 months of age has been shown to increase the risk of urinary incontinence in female dogs
•  Conformational characteristics (such as bladder neck position, urethral length, and vaginal abnormalities) may increase the risk of urinary incontinence in female dogs
•  Obesity may increase the risk of urinary incontinence in spayed female dogs
•  Other possible risk factors for urethral incompetence include breed, large body size, increased urination (known a “polyuria”) and early tail docking

Treatment

Health Care

•  Your pet’s veterinarian will assess your pet for potential causes of urinary incontinence and contributing factors
•  Most cases will be managed successfully with medication
•  Some cases will require surgical correction of anatomic problems, or injection of bulking material (such as collagen) into the urethra to prevent leakage
•  Usually as outpatient
•  Address partial obstructive disorders and primary nervous system disorders specifically, if possible
•  Identify urinary tract infection and treat appropriately

Diet

•  Weight management to prevent or treat obesity may decrease risk of urinary incontinence

Surgery

•  Developmental urinary tract disorders (such as ectopic ureters and congenital urethral hypoplasia) often can be corrected surgically; functional abnormalities of urethral competence or urinary bladder storage function may accompany the anatomic or structural disorder and require medical treatment
•  Surgical procedures and prosthetic sphincter implantation have been described for the treatment of incontinence that is poorly responsive to medical treatment; however, poor improvement has been seen in long-term follow-up

Follow-Up Care

Patient Monitoring

•  Pets receiving α-adrenergic agents—observe during initial treatment period for adverse effects of the drug, including rapid heart rate, anxiety, and high blood pressure (known as “hypertension”)
•  Pets receiving long-term estrogen—initial, 1 month, and periodic complete blood counts
•  Periodic urinalysis and urine bacterial culture (to check for possible urinary tract infection)
•  Take your pet to the veterinarian if you notice an increase in frequency of urination, an increase in urine leaking, or blood in the urine
•  Once a therapeutic effect has been observed, slowly reduce the dosage and frequency of administration of medications to the minimum required to control signs of incontinence; dosage and frequency of administration should be changed under the direction of your pet’s veterinarian
•  Consider combination treatment (α-adrenergic agents with reproductive hormones or anticholinergic agents), deslorelin or surgical options, if poor response to single-agent medication

Possible Complications

•  Recurrent and ascending urinary tract infection
•  Urine scald (skin condition that looks like a burn due to the irritation of urine on the skin)
•  Inflammation of the skin (dermatitis) and moist tissues of the vulva
•  Inflammation of the skin (dermatitis) on lower abdomen, area between rear legs and rear legs
•  Unmanageable incontinence

Expected Course and Prognosis

•  Most dogs with urinary incontinence will respond well to medications and have complete resolution of incontinence (with rare lapses)
•  Expect excellent response to medical treatment in 60–90% of treated pets
•  Some dogs will require an adjustment in medication dose or type over time (years)
•  A smaller percentage of dogs will not respond well to medication and will require combination medications, collagen injections or surgical procedures to improve continence; these dogs usually will be “improved,” but not “cured”
•  The prognosis for improvement is less optimistic for cats and for male dogs

Key Points

•  Loss of voluntary control of urination, usually observed as involuntary urine leakage
•  Medium- to large-breed dogs most often affected
•  Most common in middle-aged to old, spayed female dogs
•  Obesity may increase the risk of urinary incontinence in spayed female dogs
•  Urinary tract infection is a possible complication of urinary incontinence

Blackwell’s Five-Minute Veterinary Consult: Canine and Feline, Fifth Edition, Larry P. Tilley and Francis W.K. Smith, Jr. © 2011 John Wiley & Sons, Inc.