Urolithiasis Flashcards
signs of LUT uroliths
pollakiuria, stranguria, hematuria
signs of UUT uroliths
anorexia, malaise, sub lumbar pain, uremia, hematuria
relative supersaturation (RSS)
measures the risk of crystals forming in the urine; ratio of activity product to solubility constant
undersaturation
no crystallization
crystal dissolution
desired for urinary stone diets, urine state, etc for stone prevention and treatment
metastable supersaturation
no spontaneous crystallization
no crystal dissolution possible
labile supersaturation
spontaneous crystallization
crystal growth/aggregation
crystalluria
crystals in the urine
is crystalluria always a disease state
NO - can have crystals in health
what is a stone matrix
the material that gets incorporated into the stone lattice as it forms (protein, cell debris, foreign bodies, drug residues, etc)
if concurrent stones + crystalluria, is the stone type always the same as the crystal type
NO - can be, but not always
what stone types occur from genetic mutations in dogs
urate and cystine
what is the best diagnostic for stones
radiographs (for radio-dense stones)
ultrasound or cystourethrogram (for radio-lucent stones)
what stones are radio-dense
struvite
Ca oxalate or phosphate
what stones are radio-lucent
urate (purine) and cystine
what are other diagnostic options for stones
contrast studies (positive or double contrast), excretory urography, cystoscopy
what diagnostic is best for measuring stone size
radiographs
ultrasound OVERESTIMATES size (best option for radiolucent)
what are some methods of stone removal
cystotomy
dissolution
voiding urohydropropulsion
laser and basket retrieval
cystotomy
surgical removal of the stones
most common for all types
dissolution
dissolving the stones
only used for struvite and some urate/cystine stones
can NOT dissolve Ca stones
voiding urohydropropulsion
infusing the bladder until full, positioning the patient upright, shake and remove catheter while expressing the bladder to void stones
repeat until empty
laser and basket retrieval
laser the stone until it gets broken up; retrieve the largest piece with a basket then use VUH to empty remaining pieces
primary uroliths in dogs
Ca oxalate
struvite
urate
Ca phosphate
cystine
silica
primary uroliths in cats
struvite
Ca oxalate
urate
dried blood
Ca phosphate
where is the main site of Ca oxalate stones
dogs: bladder
cats: ureters
what pH do CaOx dihydrate stones form in
acidic
what is the signalment for CaOx stones
middle aged males
some breed dispositions
what is the best prevention for CaOx stones
serum Ca monitoring
high water intake
where is the main site of struvite stones
lower urinary tract
(can be upper in dogs)
what is the main cause of struvite stones in dogs
urease producing bacteria
always culture urine if struvite stones identified in dogs
what pH do struvite stones form in
alkaline
how do you treat struvite stones
cats: acidic diet
dogs: acidic diet + antibiotics
can you prevent struvite stones in dogs
NO - need to prevent the UTI of urease producing bacteria in order to prevent struvite stones
what enzyme converts hypoxanthine to xanthine in protein metabolism
xanthine oxidase
what enzyme converts xanthine into uric acid in protein metabolism
xanthine oxidase
where does uric acid travel to continue protein metabolism
the liver
what enzyme converts uric acid to allantoin in protein metabolism
uricase
what are the two ways of obtaining urate uroliths
- hyperuricosuria mutation
- portosystemic shunts
hyperuricosuria mutation
defective transporters prevent uric acid from entering hepatocytes, preventing conversion of uric acid to allantoin –> uric acid accumulates in circulation –> kidneys can’t reabsorb –> accumulates in urine –> forms urate stones
common in Dalmatians
how do portosystemic shunts cause urate stones
PSS causes blood to bypass the liver –> uric acid can’t reach hepatocytes –> unable to convert to allantoin –> uric acid accumulates –> forms urate stones
resolving PSS will resolve the urate stones
what stones are most common in goats
Ca carbonate (alfalfa)
struvite (grain)
what stones are most common in cows
struvite (grain)
silica (soil)
what stones are most common in horses
Ca carbonate
caused by alkaline urine
what stones are most common in chelonians
urate
caused by uric acid as final waste product
what stones are most common in rodents
Ca carbonate
what stones are most common in pigs
amorphous magnesium calcium phosphate (AMCP)
