Urination Flashcards
How is urine transported from the kidneys to the bladder?
- Via ureters, peristalsis
- Locally regulated smooth muscle
- Low pressure in renal pelvis
- Also passive due to constant pressure from urine produced in kidney
Define micturition
The normal process of passive storage and active voiding of urine
- What happens to the urine after the kidneys
How is retrograde flow back up the ureters prevented?
- Ureters enter at oblique angle to bladder
- As bladder fills, closes off the ureters
- However, retrograde flow can occur while in ureters although is prevented by peristalsis and constant pressure from kidneys
What type of muscle is present in the bladder and urethra?
- Bladder: smooth muscle
- Urethra: smooth and skeletal muscle
What is the main function of sympathetic innervation to the bladder?
- Storage
- Contracts internal sphincter preventing passage of urine
Where is the detrusor muscle?
- Network of smooth muscle fibres within bladder wall
What is the innervation to the detrusor muscle?
- Sympathetic and parasympathetic
Describe the internal urethal spincter
- Thickening of bladder muscularture
- Smooth muscle
- Sympathetic supply
Describe the external urethral sphincter
- Striated muscle fibres
- Under voluntary control of somatic nervous system
- Also used in storage
Describe the function of the sensory innervation to the bladder
- Stretch sensitive
- Nerve endings in bladder wall
- Indicate level of filling
What types of motor innervation are involved in micturition?
- Somatic
- Parasympathetic
- Sympathetic
Describe the somatic innervation of micturition (outflow, synapse, what it innervates, function)
- Outflow S1-2 (pudendal nerve)
- No synapse
- Innervates urethral skeletal muscle (external urethral sphincter)
- Function is to retain urine
Describe the parasympathetic supply to the bladder (outflow, synapse, what it innervates, neurotransmitterfunction)
- Outflow S1-3 (pelvic plexus)
- Synapse: pelvic plexus or bladder wall
- Innervates detrusor muscle
- ACh
- Excitatory, empty bladder
Describe the sympathetic supply to the detrusor muscle (outflow, synapse, neurotransmitter, receptor, function)
- Outflow: L1-4
- Synapse: caudal mesenteric ganglion (or occasionally bladder wall)
- Norepinephrine
- Beta receptor
- Inhibitory, allow bladder filling
Describe the sympathetic supply to the internal sphincter muscle (outflow, synapse, neurotransmitter, receptor, function)
- Outflow: L1-4
- Synapse: caudal mesenteric ganglion
- Norepinephrine
- Alpha-receptors
- Excitatory, retains urine and increases urethral tone
What is the significance of the sympathetic outflow to the bladder and internal sphincter?
- Same outflow
- Allows excitation of sphincter and relaxation of detrusor to allow urine storage
Describe the central connections involved in the innervation of the bladder
- Control at pons and cerebral cortex
- Some postulated control from cerebellum
- Some bladder function local (within spinal cord) , some cerebrocortical input
- Cerebral input allows control of all the processes
What is the detrusor reflex?
The reflex contraction of the detrusor muscle in order to expel urine
How is the detrusor reflex stimulated?
- Increase in bladder pressure during filling
- Detrusor stretched
- Once at certain level of stretch = reflex contraction to urinate
- Moderated in local reflex arc (no brain involvement)
- Contraction occurs against urethral sphincter tone
What is the micturition reflex?
The reflex ejection of urine from the bladder, via the urethra
- Combination of detrusor reflex with inhibition of sympathetic, and voluntary motor supply to the bladder and urethra
Describe the micturition reflex
- Voluntary or automatic
- Detrusor contraction (stimulated by increased pressure)
- Inhibits sympathetic and somatic supply to urethral sphincters
- Bladder contracts, sphincters open, urine voided
- Moderated at levels of sacral spinal and lumar spinal cord segments
What ensures complete voiding of the bladder?
- Positive feedback to destrusor
- Will be completed once initiated
Describe the automatic control of micturition
- Once bladder reaches particular pressure
- No control of detrusor muscle, only control over external urethral sphincter
- Reflex pathways, bladder empties spontaneously
Describe the voluntary control of micturition
- Suppression of autonomic reflexes to a degree, but overridden once reaches certain pressure
- Can initiate micturition at appropriate time
- Increase intra-abdominal pressure to increase bladder pressure and initiate detrusor and micturition reflex
What drugs increase sphincter tone?
Alpha-sympathomimetic
What drugs decrease sphincter tone?
- Alpha-adrenergic blockers
- Skeletal muscle relaxants
What drugs increase detrusor tone?
Parasympathomimetics
Define incontinence
Lak of voluntary control of excretory functions (can occur alongside normal micturition as is a lack of voluntary control, not dysfunction of micturition itself)
What do disorders of micturition refer to?
- Abnormalities of detrusor or sphincters
- Normal, increased or decreased activity
List clinical syndromes of disroders of micturition
- Inappropriate voidiig
- Inadequate voiding with an overflow of urine
- Increased frequency
- Reduced capacity
- Incomplete voiding
What is included in inappropriate voiding?
- Dysuria
- Stranguria
- Pollakiuria
- Nocturia
- Enuresis
What is dysuria?
Difficult or painful passage of urine
What is stranguria?
Straining or hesitancy associated with urination
What is pollakiuria?
Increased frequency of urination (small volumes)
What is nocturia?
The urge need to urinate overnight
What is enuresis?
Unconscious leakage of urine during sleep
What are the 2 general causes of incontinence?
- Neurological
- Mechanical
Why are neurological problems of incontinence more difficult to diagnose?
- Lesion in sacral region may mean only have sympathetic supply
- Or damage to lumbar region may remove sympathetic supply
Describe the clinical presentation with respect to the bladder for animals with upper motor neurone dysfunction
- Increased tone, retained reflexes (spastic paralysis)
- Absence of voluntary micturition
- Remove connection between brain and spinal cord
- High volume of urine retention
- Automatic bladder emptying possible
Describe the clinical presentation with respect to the bladder for aniamsl with lower motor neurone dysfunction
- Flaccid paralysis, areflexic
- No perineal winking
- Permanent leakage of urine as sphincters are open
- Atonic bladder, easily expressed
- Absence of voluntary micturition
- Atonic urethral sphincters
- Absent detrusor reflex
- Concurrent reduced perineal reflex and anal tone
List abnormalities of the bladder that can cause incontinence
- Ectopic ureters
- Acquired abnormalities of lower urinary tract (e.g. neoplasia, calculi, trauma)
- Functional outflow obstruction (e.g. reflex dyssynergia)
- Normal voiding with leakage (SMI)
- Secondary detrusor muscle atony
- Urge incontinence
- Cat tail pull injuries
Describe ectopic ureters as a cause of incontinence
- Congenital maformation
- Ureters entering directly into urethra
- Most common of abnormalities
- Constant dribble of urine
- If one into urethra and one normal, can get constant dribble and normal urination
Describe acquired abnormalities of the lower urinary tract as a cause of incontinence
- Trauma e.g. fistula development (openign from urethra into inappropriate space) or scarring leading to strangulation of one of pathways
- Blockage or malfomation of lower urinary tract system affects normal process of stage or voiding
Describe functional outflow obstruction e.g. reflex dyssynergia as a cause of incontinence
- Initiation of detrusor refex with reflex contraction of urethral sphincter
- Goes through all motions of urination, but none voided (as sphincter is contracted)
- Overfilling of bladder and risk of rupture
- Can be internal or external sphincter contraction
Describe sphincter mechanism incompetence as a cause of incontinence
- SMI
- Weak valve on bladder, leakage of urine
- Normal micturition but continuous low level leakage or when increased abdominal pressure
- More common in bitch
Why is sphincter mechanism incompetence more common in the bitch?
- Shorter effective length of urethra, less control
- ## Spayed bitches (hormonal interactions)
What are some treatment options for sphincter mechanism incompetence in the bitch?
- Alpha-adrenergic agonists
- Oestrogens
- Surgery (culposuspension)
Describe how secondary detrusor muscle atony can cause incontinence
- Secondary to primary problem leading to detrusor muscle damage
- Decreased/absent tone in detrusor, unable to contract and void urine
- Over-stretchig usually cause
Describe urge incontinence
- Micturition reflex innitiated at low volume
- More common with bladder mucosa irritation e.g. cystitis
- Constant dribbling urine
Explain how cat tail pull injuries can lead to incontinence
- Avulsion of sacral nerves
- Paralysis of S1, 2, 3 nerve functions
- Permanent LMN paraysis of bladder, flaccid tail
- Incontinent for life
What are the important features of a clinical exam in micturition disorders?
- History of voiding
- Assessment of bladder size
- Assessment of urethral sphincter tone
- Assess integrity of detrusor/micturition reflex
- Perineal reflex
- Full neurological assessment may be needed
How is bladder size assessed?
- Palpation
- Size (fullness) and tone
- Should feel turgid, floppy = reduced detrusor/bladder tone
- Important when suspect rupture
How is urethral sphincter tone assessed?
- Manual expression
- Should not urinate on light squeezing
- Urination would suggest loss of tone
How is the integrity of the detrusor/micturition reflex assessed?
- INcrease vesicular pressure (squeezing)
- Should promote micturition at a particular pressure
- Risk of rupture
How is the perineal reflex assessed?
- Lift tail and stimulate perineum
- Look for anal winking
- Same nerve stimulates this as does the sphincters (sacral segment)
What are some renal pathological changes that may occur due to ectopic ureters?
- Enlarged renal pelvic region
- Enlarged kidney
- Lost tone
- Thickened ureter
- Loss of architecture (distinction between layers)
- Presence of blood due to inflammation
Describe the normal defaecation and urination patterns of cows
- Tail held in horizontal position, back rounded
- No preference for elimination sites
Describe the normal defaecation and urination patterns of horses
- Raise tail when urinate
- Stretch legs out, stomach lowered to ground
- Manure patterns influenced by gender
- Stallions: sniff and defecate on top of manure pat
- mares also siff, but do not turn before defaecating
- Geldings less particular
Describe the normal defaecation and urination patterns of dogs
- Many normal postures
- Females usually squat, males usually raise
- Usually develop substrate and area preferences
Describe the normal defaecation and urination patterns of cats
- Back end lowered, straight back
- Strong substrate preferences and aversioins
Describe the use of elimination in territorial marking in horses
- Males urinate on eliminations of females
- Specific stud piles
- Mare likely to defaecate if sees another defaecating
- Mare may sniff then urinate on dung pile if not seen produced
Describe the use of elimination in territoral marking in dogs
- Mark territory using urination
- Pheromones in urine
- Different to normal urine
- More prominent in entire animlas
Describe the use of elimination in territoral marking in cats
- Urination rather than defaecation
- Smaller volume, vertical surfaces, pungent smell
- Multi-cat households
Which species use elimination behaviour in reproductive signalling
- Horses
- Dogs
- Cats
Describe elimination behaviour for reproductive signalling in horses
- Mares urinate more frequently
- Urine with more mucus
- Stand in squatting position
- Clitoral winking
Describe elimination behaviour for reproductive signalling in dogs
- Frequent urination in prooestrus
- May get bloody vaginal discharge
Describe elimination behaviour for reproductive signalling in cats
- Frequent urination
- Production of clear vulval discharge
Describe behaviour traits that facilitate house training in exotic species (meerkats, badgers, tiger quolls)
- Communal toilets
- Number of toilets near core territory
- Some latrines on boundary shared by neighbouring groups
- Provision of latrines that smell of different group encourages use of those toilets
What stimulates elimination in puppies and kittens?
- Unable to defaecate and urinate on their own
- Stimulated by mother licking caudal abdomen and perineal regions
- Stimualtes anogenital reflex = urination and defaecation
Give a general idea of the development of elimination behaviour in puppies and kittens
- Birth: unable alone, stimulated by mother
- 15 days: voluntary elimination develops
- 3-6 weeks: voluntary control acheived, follow mother to latrine site
- 12 weeks: latrine preferences fixed
- 6 months: leg cocking develops in males, onset of puberty
What is the difference between spraying and latrine behaviour?
- Spraying is to communicae
- Latrine behaviour is for elimination of urine or faeces
What are the significant features of spray marking?
- Usually in response to stress/high arousal
- Significant areas of home
- Still using appropriate latrine area for urine and faeces
- Often vertical spraying posture with tail quiver
- No evidence of physical ailment
What may cause latrine behvaiour issues?
- Medical disorders
- Latrine aversion
- Substrate preference/aversion
- Location aversion/preference
- Inadequate/loss of house training
- Lack of indoor facility
Give some situations that may result in house-soiling in cats
- Inflammatory disease of urinary system/lower bowel
- Conditions causing PUPD
- Conditions causing cognitive decline
- Historical associations with painful elimination
- Introduction of new cat
- Separation anxiety
Give some medical causes of house soiling in dogs
- Neoplastic (bladder tumours)
- Metabolic disorders (diabetes)
- Dietary
- Pain related (hip dysplasia)
- Infectious/inflammatory (urolithiasis)
- Neurological
Give some behavioural causes of house soiling in dogs
- Lack/incomplete house training
- Sexual signalling
- Social signalling
- Arousal
- Owner related
- Physical distress
- Social distress
- Secondary to psychogenic polydipsia
How can house-soiling be modified using practical techniques?
- Effective cleaning of soiled areas
- Stop punishment
- Chemical therapy to treat underying problem
- Environmental manipulations (pheromones, control of stressor etc)
- Control impact of stressor (prevent cat seeing other cats in area e.g. obscure window)
Describe treatment for inappropriate latrine behaviour in cats
- Ensure resources readily available for all cats
- Protect area (L-shpaed litter box)
- Confine for short periods if necessary
- Stop punishment
- Addess cause e.g. stress
- Create attractive latrine areas
- Retrain where necessary
Describe treatment for house-soiling in dogs
- House training
- Do not punish
- Reward appropriate behaviour
- Learn cues from dog
