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SA DX & TX II > Exam 4 - Urolithiasis > Flashcards

Exam 4 - Urolithiasis Flashcards

1
Q

____ stones generally form in alkaline urine & ______ ________ & _____ stones form in neutral to acidic urine

A

struvite - alkaline

calcium oxalate & urate stones

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2
Q

T/F: type of crystals in the urine only correlate with the type of stone only 50% of the time

A

true

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3
Q

how are uroliths named?

A

named based off of their mineral composition

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4
Q

what animals are predisposed to urethral obstruction?

A

males more than female

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5
Q

what does bladder stone formation depend on?

A

concentration of salts, adequate time in the urinary tract, favorable urine pH, absence of crystallization inhibitors (glycosaminoglycans), & a nidus upon which the salts crystalize (protein matrix)

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6
Q

urine can hold what kinds of salts during conditions of supersaturation which have the potential to form crystals?

A

calcium oxalate

magnesium ammonium phosphate

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7
Q

does crystalluria always predict the presence of stones in the bladder?

A

no

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8
Q

how does pH of urine help you determine most likely stone type?

A

certain stones form under certain pH conditions

struvite - alkaline

calcium oxalate & urate - neutral to acidic

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9
Q

why do we do a urine culture & sensitivity for patients with uroliths?

A

uroliths predispose the animal to UTIs - UTIs with concurrent urolithiasis are considered to be complicated

management of canine struvite stones requires appropriate abx therapy

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10
Q

what is the purpose of taking abdominal radiographs for a patient with uroliths? which stone types can be seen? which can’t be seen?

A

determine presence, number, size, & shape of stones - include urethra on the rad (for male dogs, take lateral pelvic rads with the pelvic limbs both hip extended & hip flexed)

you can see calcium oxalate, calcium phosphate, struvite, & silica

urate & cysteine

calcium oxalate & struvite most radiodense

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11
Q

what animals are predisposed to developing urate stones?

A

common in dalmations

seen in animals with portosystemic shunts & chronic hepatic insufficiency

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12
Q

is it okay to just do an abdominal ultrasound in a patient with uroliths and not get an abdominal radiograph? what is it useful for?

A

nope - can’t fully evaluate them for urethral stones

detecting small stones, radiolucent stones that may not be seen on rads, & looking for evidence of urethral obstruction

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13
Q

why do you need to submit all uroliths for stone analysis?

A

quantitative analysis tells us the composition of the stone & is used to guide therapy

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14
Q

what clue maybe seen on a cbc for a patient with urate uroliths that indicates an underlying disease process? what further diagnostics should you do for these patients?

A

microcytic anemia - portosystemic shunts

liver function testing

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15
Q

what imaging can be done to detect stones not visible on plain radiographs?

A

contrast radiography

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16
Q

what signalment of cat/cat breeds are predisposed to calcium oxalate stones?

A

persians & himalayans

indoor cats!

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17
Q

what is an important predisposing factor for struvite stone development in dogs?

A

UTIs - urease producing bacteria cause urine to become alkaline (pH > 7.0)

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18
Q

what are the bacterias that cause UTIs that are urease producing?

A

s. intermedius, proteus spp.

e. coli, klebsiella spp., & pseudomonas spp. sometimes produce urease

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19
Q

T/F: because of the association with UTIs, struvite stones are more common in female dogs

A

true

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20
Q

what dog breeds are predisposed to getting struvite stones?

A

mini schnauzers, mini poodles, bichon frise, & cocker spaniels

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21
Q

what are the most common shapes seen of struvite stones?

A

often smooth, blunt edged or pyramidal

can be jack shaped

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22
Q

where do struvite stones mostly form?

A

mostly in the bladder but can form in kidneys & ureters

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23
Q

what is interesting about struvite stones in cats in regards to how they form?

A

struvite stones form in the absence of a UTI but still form in alkaline urine

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24
Q

what are urate stones composed of?

A

ammonium acid urate

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25
Q

what is the common form of calcium oxalate stone seen in dogs?

A

calcium oxalate monohydrate

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26
Q

T/F: although hypercalcemia can predispose animals to calcium oxalate stones, most dogs are normocalcemic

A

true

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27
Q

a urine pH of what favors the formation of calcium oxalate stones?

A

< 6.5

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28
Q

what signalment of dogs are predisposed to calcium oxalate stones? what breeds are predisposed to getting them?

A

male dogs - often older, 8-12 years old

mini schnauzers, standard schnauzers, mini poodles, yorkies, lhasa apsos, bichons, & shih tzus

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29
Q

T/F: in dogs that have calcium oxalate stones, it is rare that they have a concurrent UTI

A

true

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30
Q

what is the common appearance of calcium oxalate stones?

A

often rosette (jagged) but can be smooth

31
Q

there is an increased incidence in urate stones in what animals?

A

dogs with liver dysfunction (especially shunts) such as mini schnauzers, yorkies, & pekingese

dalmatians (especially males) & english bulldogs due to altered metabolism of uric acid

32
Q

what do urate stones look like?

A

often small & can be jack shaped

yellow-brown or green & color

33
Q

how are mixed stones named?

A

if a stone is compromised of >70% of one type of mineral, it is named for that mineral

if there is less than 70% of one stone type, considered a mixed stone

34
Q

what is an example of how mixed stone may be unevenly mixed or deposited in layers?

A

calcium oxalate stone may be present which predisposes an animal to infection with urease-producing bacteria which makes the urine alkaline - the stone then can develop an outer layer of struvite

35
Q

what is cystinuria?

A

inherited renal tubular transport disorder that predisposes an animal to cysteine stone formation

36
Q

what breeds are predisposed to cysteine stone development?

A

english bulldogs, newfoundlands, dachshunds, irish terriers, basset hounds, & bull mastiffs

37
Q

T/F: cysteine crystalluria is always abnormal & should be investigated

A

true

38
Q

when would voiding urohydropulsion be an appropriate treatment choice for a patient with uroliths?

A

for small bladder stones with clinical signs - urethral size will dictate if this is possible!!!

stone must be <7mm in female dogs, <5 mm in male dogs, & <5 mm in female cats

39
Q

when is the only time you could use voiding urohydropulsion for a male cat with uroliths?

A

only if they have had a perineal urethrostomy surgery

40
Q

what are potential complications that may arise when using voiding urohydropulsion as a way to remove uroliths?

A

urethral obstruction, bladder rupture, & hematuria

41
Q

how is voiding urohydropulsion done to remove uroliths?

A

patient is anesthetized, bladder is distended with saline, urinary catheter is removed, patient is held upright, & steady pressure is applied to the abdomen

procedure is repeated as needed - stones are collected for submission

42
Q

when is catheter-assisted retrieval appropriate to use for removing uroliths? how is it done?

A

very small bladder stones - may not require sedation

u cath is placed & bladder is filled with saline - saline is suctioned via the catheter may contain stones

43
Q

is it okay to use voiding urohydropulsion in a patient that had recent bladder surgery?

A

NOPE

44
Q

what is the benefit of using medical dissolution for treating uroliths?

A

less invasive than a cystotomy & avoids placement of suture that can induce stone formation

cost of medical management & follow up is similar to a cystotomy

45
Q

T/F: medical dissolution can be used for calcium oxalate stones

A

false!!! can’t be used!!!!

46
Q

what is the treatment of choice for non-obstructive struvite uroliths located in the bladder?

A

medical dissolution

47
Q

what is the protocol for struvite stone dissolution?

A

for dogs - abx based on culture & sensitivity are continued throughout dissolution period (in cats, struvite stones are usually sterile)

48
Q

what diets must be fed for dissolving struvite stones in dogs & cats?

A

dogs - hill’s urinary s/d canned or royal canin urinary s/o canned and dry

cats - hill’s urinary care s/d canned & dry, hill’s urinary care c/d canned & dry, & royal canin urinary s/o canned & dry

49
Q

if medical dissolution therapy is unsuccessful for struvite stones, what should you consider?

A

were the owners compliant with the diet? urine should be isosthenuric & pH should be < 6.5

was abx therapy appropriate? reculture

stone may contain mineral that can’t be dissolved

may fail if solitary stone is very large & filling the entire bladder lumen

50
Q

what are some contraindications for stone dissolution of struvite uroliths?

A

urethral obstruction

discomfort for the patient

very young or lactating patients

51
Q

what are the risks involved in doing a cystotomy for removing uroliths?

A

experienced surgeons fail to remove all uroliths in 15% of dogs & 20% of cats - to fix this, do rads post-op

suture material in the lumen of the bladder can act as a nidus for stone formation

52
Q

when is a cystotomy indicated?

A

for calcium oxalate stones or other stones in patients that medical management isn’t an option

53
Q

when would you consider leaving uroliths in a patient?

A

stones that are sterile, asymptomatic, not dissolvable, & large enough that obstruction isn’t a concern

risk of secondary UTI, polyp formation, & patient discomfort

client must be educated about signs of obstruction

54
Q

how should you attempt to unblock an animal?

A

attempt to pass a lubricated ucath alongside the stone to empty the bladder

retrograde hydropulsion can be used to try & dislodge the stone & flush it into the bladder & then it can be removed with cystotomy or lithotripsy

55
Q

what is lithotripsy? when is it best used?

A

urolith is fragmented into pieces that can be hydropulsed or retrieved endoscopically

best for a single stone whose fragmented pieces can be hydropulsed out without excessive trauma to the urethra of urethral obstruction

56
Q

when is endoscopic basket retrieval of uroliths indicated? what animals can’t have this?

A

for stones or stone fragments < 5-7 mm

not suitable for male cats or small male dogs

57
Q

what is the common urolith type that often causes ureteral obstruction?

A

usually due to calcium oxalate stones

58
Q

why do you need immediate treatment for ureteral obstruction?

A

need urgent treatment because obstructive or partially obstructive ureterolith causes acute kidney injuries

59
Q

how is ureteral stenting done?

A

stent is placed from the bladder to the kidney bypassing the obstructing stone & causing passive dilation of the ureter (usually for dogs)

60
Q

what medical management is used for ureteral obstructions?

A

iv fluids, mannitol as a diuretic, prazosin (alpha adrenergic blocker, to decrease ureteral spasm), & analgesia

close monitoring

if no improvement after 24 hours, move to alternative treatment plans

concurrent UTIs are common in dogs with ureteral obstructions

61
Q

how is a subcutaneous ureteral bypass system performed to correct ureteral obstructions?

A

special device is surgically placed that connects the kidney to the bladder external to the ureter (usually for cats)

62
Q

what is a nephrostomy tube?

A

in kidneys with complete obstruction, a tube can be placed into the kidney & connected to an extension system outside of the body to buy time until a definitive therapy can be performed within 24 hours

63
Q

how are struvite stones prevented?

A

manage UTIs (dogs > cats)

correct/manage underlying disorders that predispose an animal to UTIs

avoid meds that predispose animals to UTIs

dietary management for prevention of sterile struvite stones (diets restricted in phosphorus & magnesium to help produce more acidic urine) or consider a canned diet to increase water intake & decrease USG

64
Q

what medications may be used for preventing struvite stones?

A

consider methionine or ammonium chloride to acidify urine if no UTI is present

abx to manage UTIs

65
Q

what monitoring can be done for preventing struvite stone formation?

A

urinalysis monthly to start & then every 3-6 months

target pH <6.5

target USG < 1.020-1.030

urine culture monthly for 2-3 months & then every 3-6 months in cases with UTI related stones

culture if signs of UTI develop

imaging if clinical signs of stones develop

66
Q

T/F: if a UTI is present, it is a complication of calcium oxalate urolithiasis, not the cause

A

true

67
Q

what dietary management is used for preventing calcium oxalate stones?

A

avoid foods high in oxalate, avoid calcium supplements, feed canned food to increase water intake (target USG in dogs <1.020, in cats <1.030)

reduced protein diets to promote diuresis & alkaline urine formation

68
Q

what are your diet options for a patient with calcium oxalate stones?

A

dogs - hill’s u/d canned & dry, hill’s g/d, royal canin urinary s/o canned & dry

cats - hill’s c/d multicare canned & dry, royal canin urinary s/o canned & dry, IAMs urinary o-modrate pH canned & dry, & purina UR urinary st/ox canned & dry

69
Q

why does limiting dietary calcium not help with preventing calcium oxalate urolith stone formation?

A

in the gi tract, calcium & oxalate bind which limits oxalate absorption

if dietary calcium is restricted there is more unbound oxalate which is absorbed

70
Q

what is the purpose of using potassium citrate for a patient with a history of calcium oxalate stones?

A

alkalinize the urine

if the urine pH is consistently <6.5 (however, pH is less important for calcium oxalate stone formation)

may inhibit crystallization of calcium oxalate & favor formation of calcium citrate in urine

71
Q

what is the purpose of using hydrochlorothiazide for a patient with a history of calcium oxalate stones?

A

increase renal tubular resorption of calcium

used for patients with highly recurrent calcium oxalate stone formers that are not hypercalcemic

72
Q

what monitoring is done for patients with a history of calcium oxalate stone formation?

A

urinalysis every 3-6 months to target a pH of 6.5-8 & usg < 1.020 for dogs & < 1.030 for cats

imaging every 6-12 months to detect stones while small enough to remove them with hydropulsion

imaging if signs of uroliths develop

73
Q

for patients without underlying liver disease, what monitoring & prevention can be done to prevent the formation of urate uroliths?

A

dietary management - low protein/purine diets (hill’s u/d, hill’s l/d, royal canin hepatic ls) & increase water intake

medications - allopurinol used in cases in which dietary therapy alone is not effective but must be combined with a low purine diet or will predispose them to xanthine stone formation & potassium citrate may be added to achieve a urine pH > 7.0

monitoring - urinalysis monthly then every 3-6 months with a goal of pH > 7 & usg < 1.020 for dogs & < 1.030 for cats

imaging (ultrasound or contrast rads) every 3-6 months

SA DX & TX II (62 decks)

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