urolithiasis Flashcards
What 2 neurological conditions can appear like a blocked bladder?
- lower motor neurone (blow L5)
- upper motor neurone (above L5)
how does lower motor neurone disease present?
–flaccid , overdistended bladder with urine leakage
how does upper motor neurone disease present?
firm and tense bladder, difficult to express. Very high bladder and urethral tone
what are the clinical signs of a blocked bladder?
straining to pass urine haematuria vom in and out of tray painful depressed licking of genitals enlarged / painful bladder
Is an obstruction an emergency?
Yes - they will be dead in 72 hours from point of obstruction
What is obstructive uropathy?
full bladder causes increased ureter and therefore tubular pressure – increased pressure in bowmans space and reduced GFR
also get vasoactive hormones that reduce renal blood flow and decrease GFR
both lead to ischaemic nephropathy
What effects can obstruction have on the bladder?
ischaemia
oedema
haemorrhage
mucosal sloughing
what systemic effects will an obstruction have?
hypovolaemia and hypotension
acidotic
what biochemical changes will happen with an obstruction?
azotaemia hyperglycaemia acidaemia hyperphosphataemia hypocalcaemia hyperkalaemia
Are sever biochemical changes from obstruction reversible?
Yes
What effect does hyperkalaemia have on the heart?
bradycardia
long PR interval
tall T waves
Vent arrhythmias
How do you manage hyperkalaemia?
IVFT
calcium gluconate to stabilise heart contractility
What is the first step in treating an obstruction?
Relieve pressure
- cystocentesis
- catheterise
What would be step 2 in treating an obstruction?
- bladder lavage
- indwelling catheter if hard to unblock or have poor urine stream
- diuresis
Do you give abx to an obstructed animal with an indwelling catheter?
No - because will get resistant UTIs
What are some options for definitive treatment of an obstruction?
- smooth muscle and skeletal relaxants if urethral
- retrograde hydropulsion
- remove calculi (cystotomy)
- urinary diversion (cystotomy tube, urethrostomy)
- ureteral surgery
what is the difference between uroliths and crystals?
Uroliths are macroscopic and cause signs
crystals are microscopic and dont cause disease
What are some consequences of nephroliths and ureteroliths?
pyelonephritis
renal failure if bilateral
renal colic
hydronephrosis
what are some signs of cystoliths?
dysuria
pollakiuria
haematuria
inappropriate urination
How can you diagnose uroliths?
contrast radiography as not all radiodense
Which uroliths cannot be seen radiographically?
urate
cystine
Which key uroliths can be seen on radiographs?
struvite
oxalate
What are some treatment options for renal and ureteral stones?
- benign neglect
- invasive surgery
- dietary dissolution
Which urolith cannots be dissolved?
calcium oxalate
What are 2 procedures to remove stones from a bladder?
- voiding urohydropropulsion
- cystotomy
What is voiding urohydropropulsion?
under GA
fill bladder with saline and hold animal upright so urethral is vertical - agitate the bladder and allow stones to settle then void bladder.
Repeat several times
give 3 d Abx
What do you do with urethral stones?
retrograde flush into bladder
How do you flush urethral stones into a bladder?
under GA
pass catheter so just behind stone and have 1 finger in rectum just behind the stone
pump fluid into urethra so walls move away from calculi them remove finger so fluid and stone go to bladder
Which uroliths can you try dissolving with diet?
structive
cystine
urate
When is surgical management indicated?
obstructed unknown stone composition failure of medical treatment other abnormalities immature animals and dont want to restrict diet owner preference
- ensure number and location of calculi known immediatley before
what are the surface characteristics of calcium oxalate?
sharp projections
mulberry shaped or smooth round uroliths
What are the surface characteristics of struvite?
- smooth
- if multiple often appear pyramidal
What are the surface characteristics of urate?
multiple and smooth
What do silica uroliths appear like?
jackstone appearance
Which uroliths are found in acidic urine?
oxalate
urate
cystine
silica
which uroliths are found in acidic to neutral urine?
oxalate
silica
which uroliths are found in alkaline urine?
struvite
hydroxyapetite
What is an important thing to remember when giving a diet to dissolve struvite uroliths?
by altering urine pH can get more calcium oxalate percipitated and risk get calcium oxalate uroliths
Why is struvite found in alkaline urine?
as struvite occurs alongside a UTI with urease producing pathogens so they cleave urea into ammonia and bicarb forming an alkaline urine
What is the appearance of calcium oxalate crystals?
dumbbell (monohydrate) picket fence (monohydrate) square envelope (dihydrate)
What is the appearance of struvite crystals?
coffin lid
what is the appearance of urate crystals?
yellow - brown thorn apple
what is the appearance of cystine crystals?
hexagonal
what is the appearance of calcium phosphate crystals?
thin prisms
Which urolith is commonly found with a UTI?
struvite
in which animals is struvite found without a UTI?
cocker spaniels
cats
What are common breeds for urate crytals and why?
dalmation english bulldog miniature schnauzer shih tzu yorkshire terrier
reduced conversion of uric acid to allantoin and defective transport of it out of urine
What can you do to treat urate stones?
reduced protein intake
allopurinol (less uric acid)
maintain urine pH at 7 ish
diuresis
Which urolith is castration responsive?
cystine
Which uroliths are more common in females?
struvite
which urolith is more common in males?
oxalate
urate
cystine
silica
If uroliths are over 1cm what are they likely to be?
struvite
what would a positive urine cyanide nitroprusside test be linked to?
cystine
which urolith is likely to form with hypercalcaemia?
calcium phosphate
which urolith is due to poor diet?
silica
what can be a complication of a cystotomy?
get signs of cystitis
