Title: Disorders of micturition
1Disorders of micturition
- Stephen P. DiBartola, DVM
- Department of Veterinary Clinical Sciences
- College of Veterinary Medicine
- Ohio State University
- Columbus, OH 43210
The Nephronauts
2Disorders of micturition
3Normal and abnormal micturition
- Normal micturition (urination)
- Filling phase
- Emptying phase
- Incontinence
- Loss of voluntary control of micturition
(urination)
4Micturition Emptying phase
5Micturition Filling phase
6Micturition Role of somatic nervous system
7Disorders of micturition
- Non-neurogenic
- Neurogenic
8Non-neurogenic disorders of micturition
- Hormone-responsive (?)
- Anatomic abnormality
- Paradoxical (obstructive)
- Post-prostatectomy
- Post-perineal urethrostomy
- Urge incontinence with UTI
- Sphincter mechanism incompetence
9Hormone-responsive urinary incontinence
- Estrogen-responsive in female dogs
- Testosterone-responsive in male dogs
- Same as sphincter mechanism incompetence or an
overlapping syndrome?
10Non-neurogenic disorders of micturition
- Anatomic abnormality
- Ectopic ureter MOST common
- Others much less common
11Ectopic ureters in dogs
- Young (lt 1 year) at presentation
- Female gt Male
- Siberian huskies, Labrador retrievers, Golden
retrievers, others - Unilateral (67) or bilateral (33)
- Terminate in vagina or distal urethra
12Ectopic ureters in dogs
Normal ureteral opening
- Usually diagnosed by excretory urography or
ultrasonography - Urethrocystoscopy may be gold standard for
diagnosis
urethra
13Ectopic ureters in dogs
Unilateral
Bilateral
Cannizzo, 2000
14Ectopic ureters in dogs
Fenestrations in ectopic ureters openings in
urethras of female dogs (Cannizzo, 2000)
15Ectopic ureters in dogs
- Often accompanied by other abnormalities
- Hydroureter
- Hydronephrosis
- Urethral sphincter mechanism incompetence
- Bladder hypoplasia
- Renal problems (pyelonephritis, renal hypoplasia)
16Ectopic ureters in dogs
- Surgery controls incontinence in only 50 of
affected dogs - Owner must be warned that many affected dogs have
coexisting sphincter mechanism incompetence and
may remain incontinent after surgical correction
17Primary sphincter mechanism incompetence in dogs
- Common in large breed spayed females
- Common breeds Doberman, giant Schnauzer, Old
English sheepdog, Rottweiler - Maximum urethral closure pressure (MUCP) lower
and functional profile length (FPL) shorter on
urethral pressure profile (UPP) in affected dogs - Bladder neck positioned more caudally on
radiographs
18Primary sphincter mechanism incompetence Role of
intra-abdominal pressure
- Intra-abdominal pressure increases in lateral
recumbency - Increases in intra-abdominal pressure cannot be
transmitted to bladder neck and proximal urethra
if these structures are displaced caudally
19Primary sphincter mechanism incompetence
Treatment
- 90 of affected female dogs respond well to
phenylpropanolamine (PPA) - 60 respond to estrogens
- Some require both PPA and estrogens
20Refractory sphincter mechanism incompetence
Collagen injection
- 50 response rate
- Response may be improved by adding
phenylpropanolamine - Injections can be repeated with similar response
rate - Expensive
- Requires technical expertise
21Refractory sphincter mechanism incompetence
Colposuspension
- Moves bladder neck cranially and lengthens
urethra - Approximately 50 response rate
- Response rate may be improved by addition of
phenylpropanolamine in some dogs - Complications transient dysuria, suture
breakdown with relapse
22Neurogenic urinary incontinence
- UMN (automatic) bladder
- Lesion cranial to S1-S3
- Partial voiding (local reflex arc intact)
- High residual volume
- Difficult to express (external urethral
sphincter lacks UMN inhibition) - Loss of voluntary control
23Neurogenic urinary incontinence
- LMN (autonomous) bladder
- S1-S3 lesion
- Partial emptying when intravesical/intra-abdomin
al pressure exceeds elasticity of urethra - Residual volume higher than UMN bladder
- Easy to express manually
- Loss of voluntary control
24Reflex dyssynergy (reflex dyssynergia)
- Detrusor contracts but urethral muscle fails to
relax
25Reflex dyssynergy a diagnosis of exclusion
- Middle-aged large to giant breed male dogs
- Watch dog urinate (normal stream initiation then
dribbling and tenesmus) - Pass urinary catheter to rule out mechanical
obstruction - Measure residual urine volume
- Normal lt 0.4 ml/kg
- Dyssynergy Often 20 ml/kg or more
26Reflex dyssynergy Treatment
- Phenoxybenzamine followed by bethanechol if
necessary - Prazosin (specific alpha-1 blocker) followed by
bethanechol if necessary - Diazepam or dantrolene if suspect striated muscle
component - Intermittent catheterization as needed to
maintain low residual volume - Complications bladder hyporeflexia, chronic UTI
- Can be frustrating to manage
27Disorders of micturition History
- Signalment
- Young animals ? Congenital disorders
- Middle-aged, medium to large breed female dogs ?
Sphincter mechanism incompetence
28Disorders of micturition History
- Differentiate loss of voluntary control from
behavior change or PU/PD - Ask about hematuria or dysuria
- Ask about previous trauma or surgery
29Disorders of micturition Physical findings
- Observe perineal region in females for wetness or
odor - Palpate bladder, urethra and prostate in males
- Perform vaginal exam in females
- Perform complete neurologic examination
30Disorders of micturition Neurologic exam
- Anal tone
- Bulbocavernosus reflex
- Perineal reflex
31Disorders of micturition Other findings
- Observe animal urinating
- Pass urethral catheter to rule out mechanical
obstruction - Collect and measure residual volume (normal, lt
0.4 ml/kg)
32Disorders of micturition Laboratory findings
- Urinalysis
- Urine culture and sensitivity
- Contrast radiography
- Rule out anatomic abnormality
- Ultrasonography
33Disorders of micturitionSpecial procedures
Cystometrogram
- Pressure-volume recording of bladders response
to filling with fluid or CO2
34Disorders of micturitionSpecial procedures
Urethral pressure profile
- Pressure tracing of urethra as catheter is slowly
withdrawn from bladder at constant speed
35Urethral pressure profile
- Maximum urethral pressure (MUP) highest pressure
recorded in urethra - Maximum urethral closure pressure (MUCP)
difference between MUP and intravesical pressure - Functional profile length (FPL) length of
urethra over which urethral pressure exceeds
intravesical pressure
36Urethral pressure profile
MUCP
FPL
FPL is most consistent MUCP more variable
37Micturition disorders Treatment
- Neurogenic Correct lesion if possible
- Anatomic Correct lesion if possible
- Paradoxical Relieve obstruction
- Urge Treat UTI
38Micturition disorders Treatment
- Hormone-responsive in females
- Diethylstilbestrol (DES) 0.1 to 1.0 mg PO ? 3-5
days followed by 1 mg PO q7d - Premarin 20 ?g/kg PO q4d or 0.6 mg total dose
q4d - Adverse effects estrus, perineal alopecia, bone
marrow suppression
39Micturition disorders Treatment
- Adrenergic agonists (urethral smooth muscle
stimulants) - Ephedrine
- Nonspecific agonist ? gt ?
- Dogs 25-100 mg PO q12h to q8h
- Adverse effects CNS stimulation, tachycardia,
hypertension - Not used much due to adverse effects
40Micturition disorders Treatment
- Adrenergic agonists (urethral smooth muscle
stimulants) - Phenylpropanolamine (PPA)
- ?-adrenergic agonist
- Dogs 1.5 mg/kg PO q12h to q8h
- Effective in 90 of dogs with sphincter mechanism
incompetence - Less CNS stimulation than ephedrine and no
significant effect on blood pressure - Off the human market
41Micturition disorders Treatment
- Adrenergic antagonists (urethral smooth muscle
relaxants) - Phenoxybenzamine
- Non-specific ?-adrenergic antagonist
- 0.25 to 0.5 mg/kg q12h to q8h
- Relaxes urethral smooth muscle
- Adverse effect hypotension
- Used for functional outlet obstruction (including
reflex dyssynergy)
42Micturition disorders Treatment
- Adrenergic antagonists (urethral smooth muscle
relaxants) - Prazosin
- Specific ?-1 adrenergic antagonist
- 0.1 mg/kg divided q8h
- Relaxes urethral smooth muscle
- Adverse effect hypotension
- Used for functional outlet obstruction (including
reflex dyssynergy)
43Micturition disorders Treatment
- Adrenergic antagonists (urethral smooth muscle
relaxants) - Acepromazine
- Phenothiazine with ?-adrenergic antagonist
effects - 0.2 mg/kg SQ q12h or 1.25 mg total dose PO q24h
for post-obstructive urethral spasm in cats - Relaxes urethral smooth muscle
- Adverse effect hypotension
44Micturition disorders Treatment
- Other non-specific smooth muscle relaxants used
for detrusor hyperactivity - Propantheline
- Oxybutynin
- Flavoxate
- Dicyclomine
45Micturition disorders TreatmentSmooth muscle
stimulants
- Bethanechol
- Parasympathomimetic with primarily muscarinic
effects - Dogs 5-15 mg PO q8h
- Cats 1.25-5 mg PO q8h
- Adverse effects Anorexia, salivation,
lacrimation, abdominal cramping, vomiting,
diarrhea - Used for detrusor hypoactivity, used in
conjunction with ?-antagonist in reflex dyssynergy
46Micturition disorders Treatment
- Striated muscle relaxants
- Diazepam
- Used to relax urethral striated muscle
- Dog 2-10 mg PO q8h
- Cat 1-2 mg PO q8h
- CAUTION IN CATS Hepatotoxicity may be observed
when administered orally - May have limited effect on feline urethral
striated muscle
47Micturition disorders Treatment
- Skeletal muscle relaxants
- Dantrolene
- Direct-acting striated muscle relaxant
- Used for urethral striated muscle spasm
- Dog 1-5 mg/kg PO q12h to q8h
- Adverse effects Hepatotoxicity