Urolithiasis Parts 1 and 2 Flashcards

1
Q

describe evaluation of crystalluria

A

urine should be evaluated in light of

  1. pH of urine
  2. sample collection technique
  3. time between collection and analysis
    -if refrigerate, ALL urine will form crystals!!! need to evaluate in original conditions (like when in bladder)

it is possible to collect a “crystal pellet” for analysis
-if lots of crystals, can centrifuge, siphon off urine, and send crystal pellet for analysis

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2
Q

describe pH or urine as relates to crystal formation

A

MOST form when urine is acidic!!

5-7: calcium phosphate, purines, calcium oxalate, cystine, silica

7-8: sterile struvite

8-9: infection-induced struvite, calcium apatite

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3
Q

review the types of crystals

A

see lecture pics and path lecture if need

ammonium URATE (not biurate, technically): dalmatians and english bulldogs and jack russell terriers prone
-also with portosystemic shunt

cystine: always 6-sided and sometimes stick together (risk factor)

amorphous: we don’t know what they are

cholesterol: not common in dogs and cats, weird rectangle thingies

lipid: common in horses and fat cats

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4
Q

describe struvite stones (5)

A
  1. most radiodense (as dense as bone)
  2. fairly large size
  3. variable shapes
  4. smooth contour
  5. often many stones
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5
Q

descrieb calcium oxalate stones (4)

A
  1. radiodense (not as much as struvite)
  2. usually small and round
  3. often not more than a dozen stones
  4. irregular surface
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6
Q

describe cystine stones (4)

A
  1. marginally radiodense
  2. usually small and round
  3. often smooth contour
  4. usually less than a dozen or so
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7
Q

describe urate stones (4)

A
  1. usually radiolucent
  2. usually small and round
  3. smooth
  4. multiple stones
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8
Q

describe the stones in terms of radiodensity

Piss On Cornell University

A

Phosphate or Struvite

Oxalate

Cystine

Urate

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9
Q

describe biochemistry of urolithiasis (4)

A
  1. hyperadrenocorticism
  2. hypercalcemia
  3. increased UTI
  4. liver disease
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10
Q

what are the most common bladder stones in dogs? cats?

A

dogs: struvite or calcium oxalate

cats: same

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11
Q

describe catheter assisted retrieval of stones

A

flush fluid in via catheter, someone bounces the bladder, suck up the small stones

good for small stones or sandy/gritty stones

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12
Q

describe voiding urohydropulsion (4)

A
  1. goals are relaxation, compliance, analgesia
    -need to take away conscious control
  2. pass catheter to distend bladder, hold animal upright, shake them, then gentle pressure squeeze bladder until exceed micturition reflex
  3. re-image to see if got all stones
  4. dogs do very well with this technique, but cat bladders are very unforgiving
    -usually develop hematuria, hospitalize overnight
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13
Q

describe cystoscopy (3)

A
  1. rigid in females, or flexible or semi-rigid also exist for dudes
  2. pass graspers and grab stone once visualize
  3. or can pass a laser fiber through and break up stone inside if too big to pull out
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14
Q

describe percutaneous cystotomy lithotomy (2)

A
  1. make a small incision in abdomen and insert a scope
  2. lots of magnification = can see/remove all the little stones and then check surface of bladder for damage once done
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15
Q

describe struvite urolithiasis

A

signalment:
infection: females, neonates, older (more common in dogs)
sterile: young adult cats

blood work: usually normal, or evidence of predisposing cause

urinalysis:
infection: alkaline
sterile: neutral
struvite crystals
+/- UTI

radiography: multiple, dense, wafer to pyramidal, smooth

can dissolve medically!!

-if correcting surgically and have a negative urine culture, consider bladder biopsy and culturing the stone as well

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16
Q

how does a struvite infection begin?

A
  1. lots of urea, metabolized by bacterial urease to ammonia
    -most common urease-producing bacteria: STAPHYLOCOCCUS!!! (gram + cocci), others too but mostly staph
  2. ammonia combines with hydrogen and forms ammonium (cation) and phosphate and magnesium
    -magnesium ammonium phosphate (struvite)
    -struvite crystals form when urine pH 7.0-7.4
  3. excess CO2 from ammonia conversion forms carbonate appatite
  4. ammonium can combine with uric acid to form ammonium urate
  5. alkaline ammonium damages mucosa
17
Q

describe risk factors for sterile struvite formation

A
  1. environment: hot climate
  2. patient:
    -chartreaux, DSH, foreign SH, himalayan, oriental SH, ragdoll
    -females or MC
    -younger
    -obese
    -indoor only
    -less physical activity

diet:
-highest Mg, P, Ca, Cl
-moderate protein
-alkalinizing
-lower water intake

18
Q

describe treatment of infection induced struvite

A
  1. surgery
  2. MIPS: minimally invasive procedures
  3. medical dissolution:
    conventional:
    -feed a modified diet (low Mg, phos, protein, acidifying, diuresing
    -administer antimicrobial
    -Abx for an average of 8 weeks: urease producing microbes (staphylococcus); bacteria are trapped in the matrix of the crystal, so give antibiotics during crystal dissolution (bacteria released as crystal dissolves)
    -ideally a potentiated beta lactam (clavamox)

alternative:
-don’t change diet (changing diet won’t prevent infection!)
-give acidifier (d,I-methionine)
-administer antimicrobial for an average of 8 weeks

19
Q

describe prevention of struvites

A

infection:
-prevent/treat UTI
-no special diet

sterile:
-modified diets!
-combo struvite/oxalate
-lower minerals
-slightly acidic to neutral pH
-diuresing

20
Q

describe urate urolithiasis

A

signalment:
-liver disease: young, small breeds, males and females equally
-without liver disease: young adult, males>females, dalmatians, english bulldog, black russell terrier

bloodwork:
-liver disease
-or normal if no liver disease

urinalysis:
-acidic
-urate crystals

radiography:
-numerous lucent round smooth ammonium urate crystals

21
Q

describe urate formation

A
  1. dietary purines and endogenous purines all enter the purine pool which are ultimately converted to uric acid and then to allantoin by nonhuman primates
  2. with liver disease, or animals with the transporter ALC2A9 gene, block uricase, so stuck with uric acid

-all classic dalmatians are classic high uric acid excreters (only 20% form stones tho)
-but made a freak second dalmatian that’s a low uric acid excreter (by breeding with an irish setter); more likely to form other types of stones
-heterozygotes are carriers, homozygous recessive mutation = high excreter

22
Q

describe urate crystal dissolution

A
  1. undersaturate urine (get rid of uric acid and ammonia in urine)
    -low protein
    -alkaline
    -increase urine volume (push out)
  2. xanthine oxidase inhibitors/allopurinol:
    -block conversion of xanthine to uric acid
    -side effects: xanthine formation (yellow)
  3. works in about 1/3 cases, some get bigger bc form xanthine
    -success rate is about 50/50
    -if going to dissolve, will dissolve within a month
23
Q

what is the difference with urate dissolution in cats?

A

allopurinol can’t be used in cats! more likely to require surgical intervention

24
Q

describe urate prevention in dogs versus cats

A

dogs:
-diet: low protein, alkaline, increase urine volume
-allopurinol

cats:
diet: low protein/purine, alkaline, increase urine volume

25
Q

describe cystine urolithiasis

A

signalment:
-young adult, MALES much more than females
-english bulldogs, newfie, dachshund

bloodwork: usually normal

urinalysis:
-acidic
-cystine crystals

radiography:
-few, marginally dense, round and smooth

metabolic defect of proximal convoluted tubule

26
Q

describe cystine management

A

CAN dissolve these!!!

  1. diet: low protein, alkaline, diuresis
    -cystine is very pH dependent!
  2. thiol drugs: breaks sulfur bond in crystals
    -d-penicillamine
    -2-MPG (NOT in cats)
  3. castration
    -type III are castration responsive; will not need further preventative once castrate if type III
    -can genetic test for type I, II, III