Exam 4 - Incontinence Flashcards
the bladder is in a _____ phase 99% of the time & in an _____ phase 1% of the time
storage
emptying
what makes up the proximal & distal urethra?
proximal urethra - composed of smooth muscle that makes up the internal urethral sphincter
distal urethra - composed of striated muscle making up the external urethral sphincter
what are the components that make up the urethral sphincter mechanism?
internal urethral sphincter, external urethral sphincter, urethral length, & position of the bladder intra-abdominally & cranial to the pelvis such that intra-abdominal pressure is applied to the proximal urethra & not solely the bladder
what spinal cord segment does the hypogastric nerve originate from?
L1-L4 in dogs & L2-L5 in cats
if the bladder is under sympathetic control, what phase is it in?
storage
what is the sympathetic control exerted on the bladder from the hypogastric nerve?
hypogastric nerve innervates the muscle via beta fibers, so when stimulated, the muscles are relaxed & the internal urethral sphincter via the alpha fibers, when stimulate, contract
beta fibers - relaxes bladder wall
alpha fibers - contracts internal urethral sphincter
what spinal cord segment does the pudendal nerve originate from?
spinal cord segment S1-S3
what does the pudendal nerve innervate?
striated muscle of the external urethral sphincter & provides voluntary input to micturition
what does the pelvic nerve innervate?
somatic nerve that innervates the detrusor muscle, so that when stimulated, the muscle contracts
if the bladder is under parasympathetic control, what phase is it in?
peeing!!!!
what spinal cord segment does the pelvic nerve originate from?
spinal cord segment S1-S3
what makes up the afferent (sensory) innervation of the urinary bladder?
pelvic nerve - parasympathetic, senses bladder filling & the need to void
hypogastric nerve - sympathetic, senses pain & over-distension
pudendal nerve - somatic, to bladder neck & urethra
voiding is coordinated in the micturition center in the pons with cerebrocortical input
why is determining age of onset of incontinence important?
some causes are congenital & some are acquired (ectopic ureters - incontinence in puppies)
T/F: urethral sphincter mechanism incompetence is more common in female dogs post-ovariohysterectomy but often occurs several years after
true
what is a normal residual volume of urine in the bladder after a patient voids?
< 0.4 ml/kg
what does a large residual volume after voiding indicate?
detrusor hypocontractility or outflow resistance
what may be felt on physical exam that can help you differentiate between an upper motor neuron bladder & lower motor neuron bladder?
UMN bladder - often large & difficult to express
LMN bladder - often large & easy to express
what reflexes will you use to determine anal sphincter tone in an incontinent patient?
perineal reflex & bulbospongiosus reflex depend on an intact pudendal nerve & intact sacral spinal cord segment of S1-S3
why do you need a urinalysis in a patient presenting with incontinence?
important to evaluate for concurrent disorders!!!
dogs with UTIs occasionally present for incontinence
UTI can be a complicating factor in a patient with incontinence
relatively dilute usg suggests an evaluation for pu/pd is warranted
what do you need to do before considering more invasive methods for managing urinary incontinence?
need to get a negative urine culture!!
UTIs are common in dogs with disorders causing incontinence (ectopic ureters, neurologic bladders)
why would an abdominal ultrasound be beneficial to do when working up a patient for incontinence?
non-invasive way to assess a patient for structural abnormalities
sometimes jets of urine can be seen entering the bladder from the ureters - normal ureters are not usually visible
when would you want to do IV urography for contrast abdominal imaging in a patient with incontinence?
evaluating a patient for ectopic ureters!!
what is the purpose of doing a urethrocystoscopy?
allows for the identification of ectopic ureters - biopsies can be obtained
may allow intervention for ectopic ureters
where does a normal ureter enter a bladder? what about an ectopic ureter?
enters the bladder obliquely near the trigone at the ureterovesicular junction
ectopic ones enter at a more distal location in the urethra or the vagina
what is the most common cause of congenital incontinence?
ectopic ureters
what is the common signalment of animals affected by ectopic ureters causing incontinence?
females > males
usually <1 year at presentation (females younger than males at presentation possibly due to longer more effective urethral sphincter mechanism in males)
increased incidence in labs, goldens, & huskies
unilateral - 2/3 of cases & bilateral - 1/3 of cases
what other conditions are ectopic ureters commonly associated with?
concurrent hydroureter, hydronephrosis, +/- pyelonephritis, urethral sphincter mechanism incompetence, bladder hypoplasia
T/F: dogs with ectopic ureters urinate normally in-between episodes of incontinence
true
how are ectopic ureters diagnosed?
urethrocystoscopy to visualize ureteral openings
contrast CT
excretory urogram
ureteral jets in the bladder seen on ultrasound make ectopic ureters less likely
what are your 2 treatment options for a patient with ectopic ureters?
- laser ablation via urethrocystoscopy
- surgical transposition - only resolves incontinence in 50% of cases (patient may have coexisting urethral sphincter mechanism incompentence)
what is urethral sphincter mechanism incompetence?
decreased tone of the urethral sphincter with normal detrusor function that is subdivided into hormone responsive & non-hormone responsive
T/F: hormone responsive urethral sphincter mechanism incompetence usually occurs several years after a dog is spayed
true
what animals are commonly affected by urethral sphincter mechanism incompetence?
common in large breed spayed female dogs
rare in male dogs & very rare in cats
how is hormone responsive urethral sphincter mechanism incompetence treated? why does it work?
estrogens - estradiol increases urethral sphincter tone & may increase sensitivity of alpha receptors in the urethra of intact female dogs
T/F: urethral sphincter mechanism incompetence is often associated with a more caudally positioned bladder (pelvic bladder) on radiographs
true
how is urethral sphincter mechanism incompetence diagnosed?
usually diagnosis of exclusion
urethral pressure profile testing can confirm the diagnosis but is seldom done
what is phenylpropanolamine used for? how does it work?
used for treating urethral sphincter mechanism incompetence in dogs (proin) - 90% of female dogs respond to it alone or it with estrogens
alpha receptor agonist that increases contraction of smooth muscle of internal urethral sphincter
what is estriol used for? how does it work?
labelled for use in dogs to treat urethral sphincter mechanism incompetence - >60% of female dogs respond to estrogens alone, but dogs with non-hormone responsive USMI won’t
mimics estradiol to increase urethral tone & increases sensitivity of urethral smooth muscle to alpha innervation (possible synergy with proin)
how are urethral collagen injections used for treating urethral sphincter mechanism incompetence?
bulking agent is injected into urethra via cystoscopy - usually temporary & has to be repeated
used in refractory cases
what is colposuspension? when may this be used?
suturing cranial vagina to the prepubic tendon in dogs with urethral sphincter mechanism incompetence & a pelvic bladder
what is lower motor neuron bladder? where is the lesion? how do you treat it?
causes loss of the detrusor reflex with decreased sphincter tone that typically causes a large bladder that is easily expressed
lesion at S1-S3 (or pelvic nerve)
diagnose & treat underlying condition - will need to do manual expression of the bladder
what is upper motor neuron bladder? where is the lesion? how do you treat it?
causes loss of detrusor reflex with increased sphincter tone that typically causes a large bladder that is difficult to express (back dogs)
lesion is located cranial to sacral spinal segments
diagnose & treat underlying condition, manual expression may be difficult & patient may need to be catheterized
T/F: in FeLV associated incontinence, you may see it with or without spinal cord lymphoma
true
what is reflex dyssynergia?
incoordination of urethral relaxation & detrusor contraction where voiding is initiated normally but is then interrupted by involuntary contraction of the external urethral sphincter causing the patient to strain unsuccessfuly
what is the management aimed at for treating reflex dyssynergia causing incontinence?
aimed at relaxing urethral sphincters
when do we see reflex dyssynergia occur?
urethral disorders such as urethral spasm in an FIC cat or certain spinal cord lesions
what is dysautonomia? what clinical signs does it cause? how is it treated?
rare, idiopathic polyneuropathy of the autonomic nervous system (sympathetic & parasympathetic) that occurs in dogs & cats
incontinence, constipation, mydriasis, & prolapsed 3rd eyelids
treatment is unrewarding - bethanechol can be tried
what is detrusor atony? what does it result in?
occurs after the bladder becomes markedly distended due to a mechanical or functional outflow obstruction due to separation of the tight junctions of the detrusor muscle
results in a large flaccid bladder with a weak or absent urine stream
what management is used for patients with detrusor atony?
treat the underlying condition & place an indwelling catheter to keep the bladder empty to try & reestablish tight junctions (can take up to 7-14 days)
bethanechol can be tried to stimulate detrusor contractions - ensure the urethra is patent first & concurrent use of prazosin or tamsulosin may relax internal urethral sphincter
what is urge incontinence? how do you treat it?
involuntary bladder contractions that result in frequent, involuntary voiding of small volumes of urine usually secondary to lower urinary tract inflammation
need to treat the underlying disease
what is paradoxical incontinence?
form of overflow incontinence that occurs when mechanical (uroliths) or functional (reflex dyssynergia) obstruction of the urethra impairs voiding
when intravesicular pressure exceeds the pressure at the site of the obstruction, urine will escape around the obstruction
what are 4 drugs that are used to decrease urethral resistance?
- prazosin/tamsulosin - alpha 1 antagonists
- phenoxybenzamine - non-specific alpha antagonist (sympatholytic)
- diazepam - skeletal muscle relaxant
- dantrolene - skeletal muscle relaxant
what are the indications for using drugs to decrease urethral resistance?
functional outflow obstruction
reflex dyssynergia
what are the indications for using drugs to increase urethral resistance?
urethral sphincter mechanism incompetence!!
what are 2 drugs that are used to decrease urethral resistance?
- phenylpropanolamine - alpha agonist (sympathomimetic)
- estriol - estrogen + increases sensitivity of alpha receptors
what are the indications for using drugs to increase detrusor contractility?
detrusor atony after prolonged bladder distension
detrusor areflexia from UMN or LMN lesion
what drug can be used to increase detrusor contractility?
bethanechol - enhances smooth muscle (detrusor) contractility (cholinergic/parasympathomimetic)
what 2 drugs can be used to increase detrusor contractility?
- propantheline - anticholinergic
- oxybutynin - anticholinergic
what are the indications for using drugs to decrease detrusor contractility?
urge incontinence
what are examples of conditions that fall into the neurogenic classification of disorders of micturition?
UMN bladder
LMN bladder
reflex dyssynergia
detrusor areflexia
what are examples of conditions that fall into the non-neurogenic classification of disorders of micturition?
anatomic abnormalities - congenital or acquired
USMI - hormone responsive & non-hormone responsive
T/F: in dogs with an UMN bladder, urine retention is common but overflow incontinence is less common
true
what are the possible side effects of estriol?
inappetence, vomiting, excess water intake, & swollen vulva
what are the possible side effects of proin?
hypertension, restlessness, & tachycardia
how does bladder positioning play into the development of urethral sphincter mechanism incompetence?
intra-abdominal pressure ends up being applied to proximal urethra & bladder in bladders that are positioned more caudally
which ectopic ureter is extramural & which is intramural?
left - extramural
right - intramural
if you want to do surgery to correct ectopic ureters in a dog, what must be done prior?
need to resolve UTIs if present
which ureter is normal?
one on top
