Disorders of micturition

1. Disorders of micturition Stephen P. DiBartola, DVM Department of Veterinary Clinical Sciences College of Veterinary Medicine Ohio State University Columbus, OH 43210 The Nephronauts

2. Disorders of micturition

3. Normal and abnormal micturition • Normal micturition (urination) • Filling phase • Emptying phase • Incontinence • Loss of voluntary control of micturition (urination)

4. Micturition: Emptying phase

5. Micturition: Filling phase

6. Micturition: Role of somatic nervous system

7. Disorders of micturition • Non-neurogenic • Neurogenic

8. Non-neurogenic disorders of micturition • Hormone-responsive (?) • Anatomic abnormality • Paradoxical (obstructive) • Post-prostatectomy • Post-perineal urethrostomy • Urge incontinence with UTI • Sphincter mechanism incompetence

9. Hormone-responsive urinary incontinence • Estrogen-responsive in female dogs • Testosterone-responsive in male dogs • Same as sphincter mechanism incompetence or an overlapping syndrome?

10. Non-neurogenic disorders of micturition • Anatomic abnormality • Ectopic ureter MOST common • Others much less common

11. Ectopic ureters in dogs • Young (< 1 year) at presentation • Female > Male • Siberian huskies, Labrador retrievers, Golden retrievers, others • Unilateral (67%) or bilateral (33%) • Terminate in vagina or distal urethra

12. Ectopic ureters in dogs Normal ureteral opening • Usually diagnosed by excretory urography or ultrasonography • Urethrocystoscopy may be “gold” standard for diagnosis urethra

13. Urethral lumen Ectopic ureters in dogs Unilateral Bilateral Cannizzo, 2000

14. Ectopic ureters in dogs Fenestrations in ectopic ureters openings in urethras of female dogs (Cannizzo, 2000)

15. Ectopic ureters in dogs • Often accompanied by other abnormalities • Hydroureter • Hydronephrosis • Urethral sphincter mechanism incompetence • Bladder hypoplasia • Renal problems (pyelonephritis, renal hypoplasia)

16. Ectopic 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

17. Primary 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

18. Primary 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

19. Primary sphincter mechanism incompetence: Treatment • 90% of affected female dogs respond well to phenylpropanolamine (PPA) • 60% respond to estrogens • Some require both PPA and estrogens

20. Refractory 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

21. Refractory 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

22. Neurogenic 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

23. Neurogenic urinary incontinence • LMN (autonomous) bladder • S1-S3 lesion • Partial “emptying” when intravesical/intra-abdominal pressure exceeds elasticity of urethra • Residual volume higher than UMN bladder • Easy to express manually • Loss of voluntary control

24. Reflex dyssynergy (reflex dyssynergia) • Detrusor contracts but urethral muscle fails to relax

25. Reflex 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: < 0.4 ml/kg • Dyssynergy: Often 20 ml/kg or more

26. Reflex 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

27. Disorders of micturition: History • Signalment • Young animals  Congenital disorders • Middle-aged, medium to large breed female dogs  Sphincter mechanism incompetence

28. Disorders 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

29. Disorders 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

30. Disorders of micturition: Neurologic exam • Anal tone • Bulbocavernosus reflex • Perineal reflex

31. Disorders of micturition: Other findings • Observe animal urinating • Pass urethral catheter to rule out mechanical obstruction • Collect and measure residual volume (normal, < 0.4 ml/kg)

32. Disorders of micturition: Laboratory findings • Urinalysis • Urine culture and sensitivity • Contrast radiography • Rule out anatomic abnormality • Ultrasonography

33. Disorders of micturitionSpecial procedures: Cystometrogram • Pressure-volume recording of bladder’s response to filling with fluid or CO2

34. Disorders of micturitionSpecial procedures: Urethral pressure profile • Pressure tracing of urethra as catheter is slowly withdrawn from bladder at constant speed

35. Urethral 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

36. Urethral pressure profile MUCP FPL FPL is most consistent; MUCP more variable

37. Micturition disorders: Treatment • Neurogenic: Correct lesion if possible • Anatomic: Correct lesion if possible • Paradoxical: Relieve obstruction • Urge: Treat UTI

38. Micturition 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

39. Micturition disorders: Treatment • Adrenergic agonists (urethral smooth muscle stimulants) • Ephedrine • Nonspecific agonist:  >  • Dogs: 25-100 mg PO q12h to q8h • Adverse effects: CNS stimulation, tachycardia, hypertension • Not used much due to adverse effects

40. Micturition 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

41. Micturition 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)

42. Micturition 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)

43. Micturition 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

44. Micturition disorders: Treatment • Other non-specific smooth muscle relaxants used for detrusor hyperactivity • Propantheline • Oxybutynin • Flavoxate • Dicyclomine

45. Micturition 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

46. Micturition 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

47. Micturition 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