Renal: Urinary Incontinence & Uroliths Flashcards
What is urinary incontinence?
Involuntary passage of urine during the storage phase of urination (inappropriate)
Musculature in bladder and urethra (3)
1) Detrusor = smooth m. in bladder, helps expel urine
2) Proximal internal urethral sphincter = smooth muscle
3) Distal external urethral sphincter = skeletal muscle
Pudendal n. innervation during micturition
Controls voluntary portion of urination via control of the somatic skeletal external urethral sphincter
Hypogastric n. innervation during micturition
> Helps you store urine
- Sympathetic innervation to the internal urethral smooth m. sphincter (constriction)
- Relaxation of detrusor m.
Pelvic n. innervation during micturition
> Parasympathetic innervation to help you PEE
- Contraction of detrusor m.
Innervation throughout micturition
1) Stretch receptors sense full bladder, send info to brain (pons)
2) Motor efferents to pelvic nerve = initiate detrusor contraction
3) Inhibition of sympathetic tone on external and internal urethral sphincter (pudendal, hypogastric)
Diagnostics involved with urinary incontinence
1) Signalment = young (congenital), large breeds more commonly
2) History = diff from PU/PD, urge incontinence, behavioral problems –> puddle size, timing, urgency
3) PE = bladder size, neurologic status, rear end anatomy
4) Minimum database = urinalysis and culture
5) Imaging = position of bladder, ureters, calculi, etc.
- Others = CBC/chem for systemic causes, uroendoscopy
Number one cause of urinary incontinence
Primary sphincter mechanism incompetence, or estrogen-responsive incontinence
Common history with primary sphincter mechanism incompetence
- Occurs +/- 3 years after spaying
- Urine leakage occurs when laying down (increased intra-abdominal pressure) or with increased parasympathetic tone
Diagnosis of urinary incontinence
Diagnosis of exclusion
Main medications for urinary incontinence (2)
1) PPA = alpha agonist, increase urethral closure pressure (give biggest dose at night, may be ineffective after prolonged use)
2) Estrogens (DES) = increase sensitivity of the urethral smooth muscle to catecholamines
Side effects of estrogen and PPA in patients with urinary incontinence
1) PPA = hypertension
2) Estrogens = clinical signs of estrus, bone marrow suppression
Surgical intervention of urinary incontinence (primary sphincter mechanism)
> Submucosal injections of collagen or Teflon
- Other = hydraulic occluder, etc.
Most common anatomic abnormality that contributes to urinary incontinence
Ectopic ureters, most commonly at the distal urethra, intramural, bilateral
Common breeds affected by ectopic ureters
- Siberian huskies
- Lab retrievers
- Golden retrievers
- Newfies
- Etc.
Common history with ectopic ureter animals
- Young animal (< 1 yr)
- Difficult house breaking
- Urinary dribbling - constant or intermittent
Gold standard for ectopic ureter diagnosis in males and females
- Excretory urograph in males with CT
- Cystoscopy in females
Common concurrent disorders with ectopic ureters
- UTI
- Pyelonephritis
- Hydroureters or hydronephrosis
- Eventual urethral sphincter mechanism incompetence
Treatment of ectopic ureters
Surgical transposition - although persistent incontinence may persist
State of the bladder with an UMN lesion
Bladder is difficult to express - external urethral sphincter tone stays in place, can’t initiate urination
State of the bladder with a LMN lesion
Large and flaccid bladder, bladder is easy to express - still some internal sphincter tone, no sensory stretch
What is reflex dyssynergy or destrusor urethral dyssynergia?
Voiding dysfunction = normal initiation of micturition, followed by a decrease in and then a sudden interruption of urine flow
Signs of reflex dyssynergy
Prolonged attempts at urination (dysuria, stranguria) with only small urine squirts eliminated
Type of dog more commonly affected by reflex dyssynergy
Middle aged large to giant breed dogs
