Incontinence

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Acquired urinary incontinence (urethral sphincter mechanism incompetence, hormone-responsive incontinence) is a common disorder of older dogs[1] characterized by intermittent involuntary urination due to urinary bladder dysfunction.

Unlike post-menopausal women with incontinence, where weakening of the pelvic floor muscles is critical to development of incontinence, changes in pelvic organ support structures may not play an important role in urinary incontinence in neutered female dogs[2], presumably due to the horizontal positioning of the pelvic floor.

Although all breeds of dogs are affected, a predisposition has been noted in the Greater Swiss Mountain Dog, Soft Coated Wheaten Terrier, Doberman Pinscher and Giant Schnauzers.

Congenital incontinence differs from acquired incontinence in the former being present virtually from birth or soon afterwards, and has different anatomical etiologies such as spina bifida, hypospadias, renal agenesis, ectopic ureters[3], ureteroceles[4][5] and rectovaginal fistulas[6].

Acquired incontinence, because of its hormone-responsive nature and higher incidence with ovariohysterectomy, is thought to involve hormone-related muscular changes within the urinary bladder and pelvic muscles, resulting in reduced urethral tone[7].

In some dogs however, incontinence may precede neutering[8] and this condition should therefore be considered a multifactorial disorder. Causes of acquired incontinence may include decreased urethral tone, caudal displacement of the bladder, a shorter urethra, hormonal deficiency, obesity, altered secretion of the hypothalamic and pituitary hormones GnRH, FSH and LH due to neutering[9], reduced levels of glycosaminoglycans within the bladder and urethral connective tissue[10] or changes in α1-adrenergic receptor populations within the urethral sphincter muscles[11].

Acquired incontinence can also be stress-induced and aggravated by post-whelping trauma to pelvic organs.

Post-neutering incontinence occurs in roughly 20% of female dogs that have been neutered post-puberty, and in pre-pubertal dogs, the incidence is less than 10%[12][13], suggesting an ovarian hormonal role in the etiopathogenesis of pelvic floor (pubococcygeus) and bladder (detrusor) muscle weakening. In large-breed female dogs, incontinence has been reported as high as 30%[14][15].

Incontinence can be exacerbated in dogs with pelvic bladder syndrome[16], where there is abnormal elongation of the bladder, persistent caudal displacement of the bladder and bladder neck into the pelvic canal on distention, an indistinct or blunted vesicourethral junction and a shortened urethra[17].

Clinically affected dogs are often middle- to old-aged neutered bitches[18] which present with a protracted history of intermittent incontinence. Passive urinary leakage is frequently observed when the dog is asleep or recumbent.

Perivulvar dermatitis and dermal hyperpigmentation due to constant urine staining may be evident in some dogs.

Blood tests and urinalysis are often unremarkable, and hematuria and cystitis are inconsistent clinical findings on cystocentesis.

Diagnosis of urethral sphincter mechanism incompetence is one of exclusion. Retrograde contrast urography, ultrasonography and excretory urography may be required to attempt to visualize and physical defects in the lower urinary tract and exclude other causes.

A differential diagnosis would include secondary incontinence associated with:

Initial treatment involves medical intervention, including drugs such as diethylstilboestrol[25], phenylpropanolamine[26][27], pseudoephedrine, ephedrine, oxybutynin, flavoxate or deslorelin[28].

Surgical intervention is usually necessary in non-medically-responsive cases and includes:

Canine acquired incontinence should be considered at worst an inconvenience rather than a reason for euthanasia.

Client annoyance with inappropriate urination in their pet is a common reason for veterinary intervention, but in unsuccessful management cases, restricting dog access to indoors or providing adequate and regularly-changed bedding may be an acceptable method of dealing with this disorder that is rarely life threatening.

This condition is also seen frequently with cognitive dysfunction in geriatric dogs, which should be addressed separately.

References

  1. Gregory SP. (1994) Developments in the understanding of the pathophysiology of urethral sphincter mechanism incompetence in the bitch. Br Vet J 150:135-150
  2. Byron JK et al (2010) Evaluation of the ratio of collagen type III to collagen type I in periurethral tissues of sexually intact and neutered female dogs. Am J Vet Res 71(6):697-700
  3. Anders KJ et al (2012) Ectopic ureters in male dogs: review of 16 clinical cases (1999-2007). J Am Anim Hosp Assoc 48(6):390-398
  4. Green TA et al (2011) Diagnosis and management of ureteroceles in two female dogs. J Am Anim Hosp Assoc 47(2):138-144
  5. Holt PE (1985) Importance of urethral length, bladder neck position and vestibulovaginal stenosis in sphincter mechanism incompetence in the incontinent bitch. Res Vet Science 39:364-372
  6. Ellison GW & Papazoglou LG (2012) Long-term results of surgery for atresia ani with or without anogenital malformations in puppies and a kitten: 12 cases (1983-2010). J Am Vet Med Assoc 240(2):186-192
  7. Noël S et al (2010) Acquired urinary incontinence in the bitch: update and perspectives from human medicine. Part 2: The urethral component, pathophysiology and medical treatment. Vet J 186(1):18-24
  8. McLoughlin MA.(2004) Management of urinary incontinence. Proc BSAVA Symp
  9. Reichler IM (2010) Urinary incontinence and puppy coat due to spaying in the bitch. An overview of pathophysiology, diagnosis and therapy. Tierarztl Prax Ausg K Kleintiere Heimtiere 38(3):157-162
  10. Ponglowhapan S et al (2011) Effect of the gonadal status and the gender on glycosaminoglycans profile in the lower urinary tract of dogs. Theriogenology 76(7):1284-1292
  11. Holt PE (1985) Urinary incontinence in the bitch due to sphincter mechanism incompetence: Prevalence in referred dogs and retrospective analysis of sixty cases. J Small Anim Pract 26:181–190
  12. Veronesi MC et al (2009) Spaying-related urinary incontinence and oestrogen therapy in the bitch. Acta Vet Hung 57(1):171-182
  13. Stacklin-Gautschi NM, Hassig M, Reichler IM, et al (2001) The relationship of urinary incontinence to early spaying in bitches. J Reprod Fertil Suppl 57:233-236
  14. Fowler JD, Rawlings CA, Mahaffey MB, et al (2000) Immediate urodynamic and anatomic response to colposuspension in female beagles. Am J Vet Res 61:1353-1357
  15. Rawlings CA, Barsanti JA, Mahaffey MB, Bement S. (2001) Evaluation of colposuspension for treatment of incontinence in spayed female dogs. JAVMA 219(6):770-775
  16. Mahaffey MB, Barsanti JA, Barber DL, Crowell WA. (1984) Pelvic bladder in dogs without urinary incontinence. JAVMA 184(12):1477-1479
  17. Adams WM, DiBartola SP. (1983) Radiographic and clinical features of pelvic bladder in the dog. JAVMA 182(11):1212-1217
  18. de Bleser B et al (2011) The association between acquired urinary sphincter mechanism incompetence in bitches and early spaying: a case-control study. Vet J 187(1):42-47
  19. Fisher SC et al (2013) Constrictive myelopathy secondary to hypoplasia or aplasia of the thoracolumbar caudal articular processes in Pugs: 11 cases (1993-2009). J Am Vet Med Assoc 242(2):223-229
  20. Saey V et al (2010) Neuritis of the cauda equina in a dog. J Small Anim Pract 51(10):549-552
  21. Baiker K et al (2011) Polymyositis following Vogt-Koyanagi-Harada-like syndrome in a Jack Russell terrier. J Comp Pathol 144(4):317-323
  22. McLoughlin MA (2011) Complications of lower urinary tract surgery in small animals. Vet Clin North Am Small Anim Pract 41(5):889-913
  23. Kieves NR et al (2011) Vaginal resection and anastomosis for treatment of vestibulovaginal stenosis in 4 dogs with recurrent urinary tract infections. J Am Vet Med Assoc 239(7):972-980
  24. Krimer PM & Duval JM (2010) Pathology in practice. Postsurgical urinary incontinence caused by gossypiboma in a dog. J Am Vet Med Assoc 236(11):1181-1183
  25. Hill K et al (2012) Medical therapy for acquired urinary incontinence in dogs. Int J Pharm Compd 16(5):369-375
  26. Byron JK, March PA, Chew DJ, DiBartola SP. (2007) Effect of phenylpropanolamine and pseudoephedrine on the urethral pressure profile and continence scores of incontinent female dogs. J Vet Intern Med 21(1):47-53
  27. Claeys S et al (2011) Clinical evaluation of a single daily dose of phenylpropanolamine in the treatment of urethral sphincter mechanism incompetence in the bitch. Can Vet J 52(5):501-505
  28. Palm J & Reichler IM (2012) The use of deslorelin acetate (Suprelorin®) in companion animal medicine. Schweiz Arch Tierheilkd 154(1):7-12
  29. Claeys S et al (2010) Acquired urinary incontinence in the bitch: update and perspectives from human medicine. Part 3: The urethral component and surgical treatment. Vet J 186(1):25-31
  30. Byron JK et al (2011) Retrospective evaluation of urethral bovine cross-linked collagen implantation for treatment of urinary incontinence in female dogs. J Vet Intern Med 25(5):980-984
  31. Currao RL et al (2013) Use of a Percutaneously Controlled Urethral Hydraulic Occluder for Treatment of Refractory Urinary Incontinence in 18 Female Dogs. Vet Surg Jan 8
  32. Reeves L et al (2013) Outcome after placement of an artificial urethral sphincter in 27 dogs. Vet Surg 42(1):12-18
  33. Claeys S et al (2010) Transobturator vaginal tape inside out for treatment of urethral sphincter mechanism incompetence: preliminary results in 7 female dogs. Vet Surg 39(8):969-979