Urinary incontinence

Urinary incontinence or the loss of voluntary control of micturition is mostly seen in older dogs. Here’s how to diagnose and treat it.

Urinary incontinenceWhat is urinary incontinence?

Urinary incontinence can be defined as the loss of voluntary control of micturition. It occurs for a varieaty of reasons, and treatment should be based on an accurate diagnosis. In the dog and cat, urethral closure is not accomplished by a single anatomic sphincter, but is primarily the result of smooth muscle tone along the entire urethra in female dogs and along the proximal fourth of the urethra in male dogs. When the urethral closure pressure is greater than the bladder pressure, urine remains stored in the bladder until voluntary urination occurs. When bladder pressure increases above urethral closure pressure, incontinence occurs. Other types of incontinence include neurogenic incontinence, nonneurogenic incontinence, paradoxical incontinence, and miscellaneous incontinence.

What are the causes of incontinence?

Neurogenic incontinence may be seen in animals with spinal cord disease or trauma. Intervertebral disk disease, vertebral fractures, inflammation, or neoplasia of the spinal cord can disrupt normal neural function to this region of the urinary system, resulting in a paralytic bladder. In these animals, the bladder overdistends with urine, increasing intravesical urine pressure and resulting in dribbling of urine.

Nonneurogenic causes of incontinence include cogenital abnormalities such as ectopic ureters, patient urachus (seen in younger animals), endocrine imbalances after ovariohysterectomy (estrogen deficiency), urethral sphincter mechanism (degenerative changes, urinary surgery), and hypercontractile bladder.

Paradoxic incontinence occurs in patients with partial obstruction of the urethra. This situation is encountered most frequently in male dogs. The bladder becomes overdistended with urine, which cannot pass because of some type of obstruction, increasing the intravesical pressure above that of the urethra and causing incontinence.

Miscellaneous causes can include primary diseases of the bladder, which result in replacement of normal bladder wall smooth muscle tissue with fibrous or neoplastic tissue. Classification of urinary incontinence is shown in the Table below.

Clinical signs

  • Owner reports urine leakage when the pet is sleeping or exercising.
  • Perineal area of pet is always wet.
  • Signs of concurrent urinary tract disease are present.
  • Older spayed female dogs and noncastrated male dogs are predisposed to this condition.

Diagnosis

  • A complete physical and laboratory workup is needed to diagnose the specific cause of your pet’s incontinence.
  • Urinalysis.
  • Radiology/cystography.
  • Serum chemistries to rule out polyuria from endocrine disease.

Treatment

  • Treatment should be based on determination of a specific cause.

Words of caution

  • Medication doses may need to be adjusted to achieve success in stopping the incontinence.
  • Drugs used to treat incontinence cannot be used in pets who have other health problems such as glaucoma, diabetes mellitus, hyperthyroidism, or cardiac disease.
  • Avoid use of phenylpropanolamine in animals with glaucoma, hypertension, diabetes mellitus, and prostatic hypertrophy.
  • Side effects from anticholiinergic medications include sedation, ileus, vomiting, constipation, dry mouth, dry eyes, and tachycardia. Their use is contraindicated in patients with glaucoma.
  • If the incontinence is due to trauma or inflammation, it may correct itself with time.
  • If the incontinence is due to paralytic bladder, you may need to catheterize your pet several times daily or manually express the bladder to prevent overfilling.

(Dr M Chandrasekar, M V Sc, Ph D, is Assistant Professor, Dept of Veterinary Clinical Medicine, Ethics and Jurisprudence, Madras Veterinary College, Chennai.)

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