Equis ISSN 2398-2977

Incontinence

Contributor(s): Graham Munroe, Han van der Kolk

Introduction

  • Intermittent or continuous dribbling of urine unrelated to micturition.
  • Cause- 3 basic types:
    • Upper motor neuron diseases (UMN).
    • Lower motor neuron diseases (LMN).
    • Myogenic causes.
  • Signs: history and clinical signs depend on the specific cause but constant or periodic urine dribbling from the vulva or penis leads to urine scalding.
  • Diagnosis: rectal palpation and bladder/urethral pressure measurements are useful in categorizing the type of incontinence. Exclude frequent urination in cases of estrus behavior and colic, eg left ventral colon impaction present in the pelvic cavity.
  • Treatment: depends on the specific cause, but should consist of support specific to the bladder and general support to the animal whilst hoping for a spontaneous recovery.
  • Prognosis: poor in most cases.

Pathogenesis

Etiology

Reflex or UMN bladder 'spastic or autonomic'

Pathophysiology

  • Intermittent or continuous dribbling of urine unrelated to micturition.
  • Control of bladder function is complex and disruption can originate at a number of sites.
  • 3 basic types of incontinence:
    • Reflex or upper motor neuron (UMN) bladder (spastic or autonomic).
    • Paralytic or lower motor neuron (LMN) bladder.
    • Myogenic or non-neurogenic bladder.
  • The last two types can be associated with the atonic bladder syndrome.
  • UMN dysfunction  →   an inability to void urine consciously but the detrusor muscle can still be activated once the bladder is filled beyond threshold volume   →   reflex urination, often relatively frequently. Other severe neurologic signs will be present often   →   recumbency and possibly death.
  • LMN damage  →   detrusor muscle dysfunction, the bladder becomes atonic and greatly distended. Other signs of LMN and lumbosacral nerve dysfunction will be present.
  • Vaginal malformations, including strictures and polyps may   →   incontinence by impairing external urethral sphincter function or causing urine pooling in the vagina.
  • Hypoestrogenism-induced incontinencemay be linked to the modulating effect of estrogen on the effects of norepinephrine on alpha-adrenergic receptors in the internal urethral sphincter.
  • Sabulous urolithiasisinvolves the slow accumulation of large amounts of sabulous or mucoid urinary sediment or sludge in the bladder (mainly calcium carbonate crystals)   →   over time the sediment and urine accumulation progressively stretch the detrusor muscle   →   incontinence when the cranial bladder aspect begins to protrude over the edge of the pubis, further stretching the bladder muscle and preventing normal contraction and micturition. Further stretching prevents depolarizing waves passing between muscle fibres   →   further exacerbation of over-distention   →   interference with sphincter function   →   incontinence. This syndrome may occur as a secondary problem where bladder retention of urine happens for any length of time. Secondary cystitis, particularly in association with urine retention can   →   mucosal wall irritation/inflammation and further damage to bladder wall musculature.
  • Cystitis and chronic urethritismay   →   apparent incontinence by irritating stretch receptors in the bladder wall which subsequently stimulate involuntary detrusor contractions   →   an apparent increase in frequency of urination with a lack of control, ie urge incontinence.
  • Ectopic uretercases where the bladder is much smaller than usual may also exibit urge incontinence.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Schott II H C (2006)Urinary incontinence and sabulous urolithiasis: chicken or egg?Equine Vet Educ18(1), 17-19 VetMedResource.
  • Keen J A & Pirie R S (2006)Urinary incontinence associated with sabulous urolithiasis: a series of 4 cases.Equine Vet Educ18(1), 11-16 VetMedResource.
  • Gehlen H & Klug E (2001)Urinary incontinence in the mare due to iatrogenic trauma.Equine Vet Educ13(4), 183-186 VetMedResource.
  • Holt P E & Mair T S (1990)10 cases of bladder paralysis associated with sabulous urolithiasis in horses.Vet Rec127, 108 PubMed.
  • Clark E Set al(1987)Cystometrography and urethral pressure profiles in healthy horse and pony mares.Am J Vet Res48, 552 PubMed.
  • Kay A D & Lavoie J P (1987)Urethral pressure profilometry in mares.JAVMA191, 212 PubMed.


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