Disorders of Micturition


Chapter 83 Disorders of Micturition



Micturition involves the passive storage and the active voiding of urine. Processes that interfere with the storage and voiding of urine are termed micturition disorders. The loss of voluntary control of micturition is defined as urinary incontinence.


Most cases of micturition disorders have been reported in middle-aged and geriatric dogs. The clinical importance of these disorders is twofold:








NORMAL ANATOMY AND PHYSIOLOGY OF THE URINARY BLADDER


In order to recognize the many possible manifestations of micturition disorders it is imperative to understand the anatomy of the bladder, its functional composition, and the neurophysiology of micturition.




Nervous Control


Nervous control of the bladder and urethra is a combination of autonomic and somatic interactions. The micturition reflex is integrated by numerous interneurons and synapses between the sympathetic and the parasympathetic systems.







ETIOLOGY OF MICTURITION DISORDERS AND INCONTINENCE


Disorders of micturition and continence can be divided broadly into two types: neurogenic and non-neurogenic (Table 83-1).


Table 83-1 DISORDERS OF MICTURITION




























































































































Type of Disorder Clinical Signs Treatment
Neurogenic
Lower motor neuron bladder Distended, easily expressed No effective therapy,
Continuous incontinence Manual expression 3–4 times daily
No perineal or bulbospongiosus reflex Trial with bethanechol chloride
No detrusor reflex Concurrent antibiotics
Upper motor neuron bladder Large, firm bladder Aseptic intermittent catheterization
Difficult manual expression initially Concurrent antibiotics
Increased sphincter tone ± detrusor reflex Antispasmodics or smooth muscle relaxants
Long-term management usually frustrating
Detrusor-urethral dyssynergia Large, non-expressible bladder Prazosin
Initiation of urine stream with abrupt disruption of urination Other alpha-antagonists
Baclofen
Intact spinal reflexes Diazepam
Bladder easily catheterized Dantrolene
Non-neurogenic
Hormone-responsive incontinence Older, neutered animal Diethylstilbestrol (females)
Voluntary control of urination with intermittent incontinence Testosterone (males)
Phenylpropanolamine
Incontinence usually when relaxed or asleep
Urethral incompetence (stress incontinence) Loss of voluntary control when placed in a stressful situation or at rest Phenylpropanolamine
Imipramine
Ability to urinate voluntarily
Urge incontinence (detrusor hyperreflexia) Frequent small urinations Flavoxate
Hyperreflexive detrusor Oxybutynin
Urine spraying Dicyclomine
Stranguria Propantheline bromide
Overdistension atony Large flaccid bladder Remove mechanical obstruction
Continuous incontinence Indwelling bladder catheterization
Large residual urine volume Bethanechol chloride
Intact perineal and bulbospongiosus reflex
No detrusor reflex
Paradoxical incontinence Stranguria Remove obstruction
Persistent urine dribbling Indwelling catheterization
Large, turgid bladder that is difficult to express Surgical exploration
Cystoscopy
Ectopic ureter(s) Continuous or intermittent dribbling of urine Surgery
Ability to urinate voluntarily Phenylpropanolamine
Pelvic bladder Loss of voluntary control when placed in a stressful situation or at rest Phenylpropanolamine
Surgery
Ability to urinate voluntarily


Neurogenic Disorders


There are three types of neurogenic disorders: lower motor neuron, upper motor neuron, and detrusorurethral dyssynergia.






Non-Neurogenic Disorders


A number of disorders resulting in urinary incontinence are non-neurogenic in origin. A brief description of each disorder follows.






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Aug 27, 2016 | Posted by in SMALL ANIMAL | Comments Off on Disorders of Micturition

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