Micturition Disorders

Question 1

What nerve is responsible for PSNS innervation of the bladder, when activated causes urination?

Answer 1

Pelvic nerve

-also carries sensory information from the bladder wall)

Question 2

What nerve is responsible for SNS innervation o the bladder and when activated causes bladder relaxation?

Answer 2

Hypogastric nerve

Question 3

What nerve carries somatic motor fibers causing contraction of the external urethral sphincter?

Answer 3

Pudendal

Question 4

Describe the urinary cycle??

Answer 4

Passive phase of filling
—> hypograstric activate B receptors allowing bladder stretching
—> activate a1-receptors of trigone and proximal urethra
Blocks PSNS

Active phase (voiding)
—> Reflex: stretch receptors to pelvic nerve to spinal cord, brain stem, stimulate PSNS
—> contraction of bladder wall

—>pudendal nerve decrease urethral sphincter tone (can be over ridden at cerebrum)

Question 5

Large distended bladder
Difficult to express

Is this UMN or LMN bladder??

Answer 5

UMN —> detrusor areflexia and sphincter hyperreflexia

Question 6

Large bladder, easily expressed, constantly leaks

Is this a UMN or LMN bladder?

Answer 6

LMN

Question 7

Rx for UMN bladder?

Answer 7

Baclofen (antispasmodic, acts as inhibitory neurotransmitter and skeletal muscle relaxant)

Question 8

What is detrusor-sphincter reflex dyssynergia?

Answer 8

With initiation of detrusor contraction, the urethral sphincter spasms

Question 9

Rx for detrusor-sphincter reflex dyssynergia?

Answer 9

A-adrenergic blockers (phenoxybenzamine, prazosin, and tamulosin)

Question 10

What is dysautonomia??

Answer 10

Rare disease whete the autonomic system is damaged

Affecting all systems
Usually presents and GI disease (ileus and dilated GI)

Poor prognosis

Question 11

What causes detrusor atony?

Answer 11

Overfill (obstruction)

Large flaccid bladder
Neurological exam in normal

Question 12

What is the RX for detursor atony?

Answer 12

Manual expression of the bladder

-usually is not persistent

Question 13

What is detrusor instability/detrusor hyperreflexia?

Answer 13

Detrusor contraction during storage OR

Low compliance of detrusor

Question 14

Clinical signs associated with detrusor instability/detrusor hyperreflexia ??

Answer 14

Pollakiuria, stranguria, and dysuria

Question 15

What is the RX for detrusor instability/ detrusor hyperreflexia ???

Answer 15

Anticholinergic. — oxybutynin, imipramine, or dicyclomine

Causes relaxation of bladder wall

Question 16

What are the mechanisms that cause urinary incontinence?

Answer 16

Intravesicular pressure is greater than urethral pressure

Anatomic abnormalities

Question 17

What is the most common etiology of urinary incontience??

Answer 17

Urinary sphincter mechanism incompetence (SMI)

Question 18

What is the DDX for urinary incontinence?

Answer 18

Neurological dz - LMN

Anatomical dz

• ectopic ureters
• vaginal stricture
• pelvic bladder
• ureterocele
• ureterovaginal fistula

Question 19

What diseases have an apparent incontinence, but is not actually incontinence??

Answer 19

Pollakiuria
PU/Pd
Behavioral issues

Young bitches with hooded vulva

Question 20

What is the signalment and usual presentation of urinary spinchter incompetence?

Answer 20

Spayed bitch
Incidence higher in large breed dogs

Soiled perineal coat, urine scale, anatomical corrected
No neuro deficits

Question 21

What is urethral tone dependent on?

Answer 21

Urethral length
Reproductive status
-estrogen effect (thinner mucosal wall)
-lower number of a1 receptors

Question 22

Why are spayed females more predisposed to urinary incontinence ?

Answer 22

Lack of estrogen —> decreased sensitivity of the smooth muscle to sympathetic stimulation

Urinary sphincter pressure pre-spay = 18cmH2O
Post spay = 10cmH2O

Type I smooth fibers (responsible for continence) decrease after OVH

Question 23

What are indications for urethral pressure profiles?

Answer 23

Urethral sphincter mechanism incompetence

Detrusor instability

Reflex dyssynergia

Neurogenic abnormalities

Question 24

What is the treatment for urinary incontinence?

Answer 24

Ephedrine/phenylpropanolamine —> a1 agonists

Estriol —> increased striated muscle

Question 25

What are some associated side effects to estriol therapy?

Answer 25

Anorexia 
Emesis 
Swelling of the vulva 
Mammary hyperplasia 
Attractiveness of males 
Metorrhagia

Question 26

When is estriol therapy contraindicated ?

Answer 26

Immature bitches with congenital USMI

Question 27

What non-drug therapies can be used to treat urinary incontinence?

Answer 27

Collagen implantation —> good outcome, procedure may need to be repeated over lifetime

Colposuspension and urethropexy -> currently accepted but has limited improvement and high complication rate

Transobturator vaginal tape inside out for treatment of urethral sphincter mechanism incompetence -> fairly good owner satisfaction and continence

Question 28

What would you expect to find on clinical exam of a dog with ectopic ureters?

Answer 28

Wet coat
Inflamed perineum
Excoriations

Question 29

How can ectopic ureters be diagnosed?

Answer 29

Contrast enhanced (excretory urogram) CT and cystoscopy

IVP and CT can have false postives

Question 30

What is the treatment of choice for ectopic ureters?

Answer 30

Cystoscopic laser ablation