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51 Cards in this Set
- Front
- Back
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Explain how higher centers are used to coordinate micturition
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Pons coordinates bladder and urethral fxns
Cortical, thalamic input to pons REQ'D for voluntary inhibition and intiation of voiding |
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What is the fxn of the hypogastric nerve
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Sympathetic
α-receptors on internal muscle of urethral sphincter and neck of bladder facilitate storage (cause smooth muscle constriction when excited) β-receptors in body of bladder facilitate storage (cause inhibition of detrusor muscle or relaxation) |
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What is the fxn of the pelvic nerve
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Cholinergic
Stimulation causes contraction of detrusor and voiding |
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What is the fxn of the pudendal nerve
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Somatic components
Nicotinic cholinergic receptors Innervates skeletal muscle of urethral sphincter and pelvic muscles |
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True/False: A true urethral sphincter is not present
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True
Muscle layers form a vessicourethral jxn |
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What is the difference b/t IUS and EUS
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Internal- smooth muscle in detrusor muscle and parts of proximal urethra
External- skeletal muscle surrounding urethra just distal to IUS |
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What do inhibitory cortical signals do to micturition (to promote urination)
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Inhibit hypogastric and pudendal nerves (releases detrusor from adrenergic stimulation) and causes relaxation of EUS
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What type of signals descend the reticulospinal tracts and pelvic nerve to cause detrusor contraction and voiding
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Parasympathetic
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What are the two categories of voiding phase disorders
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Anatomic Obstructions- mucus plugs, tumors, stones
Fxnl Causes- usually do not cause azotemia or systemic signs (problems w/ nerves or muscles) |
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Explain how UMN lesions affect voiding
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Lesions b/t pons and L4 (i.e. IVDD)
These p have uninhibited contraction of the urethra (pudendal nerve) b/c of lack of inhibition by higher centers Also, loss of input from bladder to higher cventers and loss of motor pathways to bladder |
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What are the characteristics of an UMN bladder
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Large and turgid, but not as big as LMN
Hard to express! Often have paradoxical incontinence |
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How do you tx UMN bladders
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Correct underlying problem
Keep bladder pretty empty via expression or catheterization Check UA b/c prone to infection Drugs for hypertonic urethra |
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What are the drugs used for hypertonic urethra (i.e. UMN bladder)
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α-blockers (Prazosin, Phenoxybenzamine) for IUS
Diazepam for skeletal muscle of EUS |
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How do LMN lesions affect micturition
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Lesion of L4-sacral segments
Loss of motor and most sensory fxn to bladder and urethral sphincter muscles |
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What type of lesion are you likely to see a mixed micturition disorder (voiding and storage)
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LMN
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What are the characteristics of a LMN bladder
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Large and flaccid
Easily expressed b/c sphincter tone of urethra is decreased These p usually have significant other LMN problems |
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What is the tx for LMN bladder
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Correct underlying disorder
Keep bladder relatively empty via expression or catheter Monitor for infection Drugs for hypocontractile bladder +/- hypertonic urethra |
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True/False: A reflex arc can develop over time in cases of UMN bladder
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True
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What drugs are useful for tx of hypocontractile bladder (i.e.LMN)
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Cholinergics like Bethanechol
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What is detrusor atony
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A myogenic functional cause of voiding disorder
Overdistention of the bladder causes stretching/tearing of muscle fibers Usually secondary to urethral obstruction (esp. cats) |
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What are the bladder and voiding characteristics of a case of detrusor atony
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Large bladder
Normal to flaccid tone Weak stream, if attempt at all |
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What is the tx for detrusor atony
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Foley for 72hrs to keep empty and see if fxn returns (culture urine at end of catheter)
Express 4-6x/day after removal of catheter Drugs for hypocontractile bladder +/- hypertonic urethra to decrease workload on detrusor muscle (as needed) Monitor for infection |
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What are three disorders that can cause fxnl muscle weakness that translates into detrusor weakness
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HypoK+
HypoCa2+ Dysautonomia |
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Explain urethral spasm
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Inflammation of urethra causes uncontrolled spastic contraction
Common after anatomic obstruction, esp. in cats Tx w/ drugs for hypertonic urethra (Prazosin, Phenoxybenzamine, Diazepam); can also give anti-inflammatories |
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How common is incontinence in cats
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Rare
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Where do ectopic ureters usually terminate
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Urethra
Vestibule Vagina (in order of likelihood) Can be uni- or bi-lateral |
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30-40% of cases of Ectopic Ureters also have what
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Concurrent sphincter mechanism incompetence (SMI)
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What is the most accurate diagnostic for ectopic ureters
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Cystoscopy
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If the ectopic ureter is unilateral or there is hydronephrosis, then what
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Can perform nephrectomy
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What are two other names for Urethral Sphincter Mechanism Incompetence (SMI)
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Spay incontinence
Hormone responsive incontinence |
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What is the most common cause of urinary incontinence in female dogs
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SMI
Lack of estrogen/testosterone or excess of gonadotropins causes decreased number OR responsiveness of adrenergic receptors on sphincter mechanism |
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True/False: Dogs w/ SMI often have normal self-initiated voiding
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True
There is just incontinence when resting or changing positions |
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What is the typical signalment of SMI
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3x more likely if >20kg
Females almost exclusively Usually w/in 3yrs of OHE |
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Incontinence in a neurologically normal, adult FS dog w/ concentrated and non-inflammatory urine is almost always
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SMI
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If SMI does occur in a male, when does it usually happen
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10days-18mths after castration
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What is the first line of tx for SMI
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α-agonist PPA to tighten up the sphincter
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What is the second line of tx for SMI
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Add hormones if spayed/neutered
Estrogen- monitor CBC q few mths Testosterone- can cause aggression |
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Combo of α-agonist and HRT makes how many SMI dogs continent
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95%
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How is GnRH used to tx SMI
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Causes initial surge in FSH/LH, but then almost completely suppresses and see continence in some
(α-agonists and HRT preferred, though) |
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Besides GnRH analogue, what other alternative tx for SMI exists
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Urethral bulking procedure (inject agents into submucosa) to obstruct urethra so need more pressure to overcome it
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How successful are cystourethropexy and culposuspension for tx of SMI
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Almost always fail eventually
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What is the most common cause of incontinence in the male dog
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Prostate dz
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What is urge incontinence
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Several disorders cause increased intensity or frequency of the normal reflex that causes inappropriate urination and pollakiuria (the reflex is normal for the dz condition though)
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What are 2 examples of parasympathomimetics for tx of hypocontractile bladders (LMN, detrusor atony)
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Bethanechol
Metoclopramide |
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What muscarinic anticholinergics can be used to tx hypercontractile bladders (urge, detrusor instability)
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Propanthalene
Oxybutynin Tolteridine Dicyclomine |
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What is detrusor instability
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Idiopathic bladder spasticity
Looks like urge incontinence |
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What β-sympathomimetic can be used to treat hypercontractile bladders (urge, detrusor instability)
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Terbutaline
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Besides muscarinic anticholinergics and β-sympathomimetics, what other drug can be used to tx hypercontractile bladders
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Amitriptylline
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Which α-sympathomimetics can be used to tx hypotonic urethras (SMI)
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PPA
Pseudoephedrine |
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Which hormones can be used to treat hypotonic urethras (SMI)
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Diethylstilbestrol
Methyltestosterone |
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Which drugs can be used to treat hypertonic urethras (spasm, UMN lesions, dyssynergia)
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α-sympatholytics (smooth muscle)- Prazosin and Phenoxybenzamine
Diazepam (skeletal muscle) |
