Urolithiasis (Yr 4)

Question 1

what are the top three uroliths?

Answer 1

struvite
calcium oxalate
cystine

Question 2

what appearance do calcium oxalate dihydrate crystals have?

Answer 2

envelopes

Question 3

what appearance do struvite crystals have?

Answer 3

coffin lids

Question 4

what appearance to rate crystals have?

Answer 4

thorny apples

Question 5

what appearance do cystine crystals have?

Answer 5

hexagons

Question 6

what are the first tests to run when uroliths are identified?

Answer 6

USG and pH
(culture - possible UTI)

Question 7

what uroliths form in acidic conditions?

Answer 7

calcium oxalate
purines
cystine

Question 8

what uroliths for in alkaline urine?

Answer 8

struvites

Question 9

what uroliths can be treated medically?

Answer 9

struvite
urate
cystine
(all dissolve with diet/therapy)

Question 10

what are indications for surgical removal of calculi?

Answer 10

obstructions
increase in size/number of calculi
persistent clinical signs
lack of response to therapy

Question 11

what pH does struvite form in?

Answer 11

alkaline

Question 12

what is the predisposing factor which has to be present for struvite uroliths to form?

Answer 12

UTI (in dogs)

Question 13

can struvites be seen on radiographs?

Answer 13

yes (radiopaque)

Question 14

why does a UTI cause struvite stones?

Answer 14

urease produced by bacteria causes production of ammonia and bicarbonate from urea which cause pH to fall and irritation of the wall leading to cells being shed and forming the centre of a urolith

Question 15

how are struvite crystals treated?

Answer 15

reduced protein, phosphorus and magnesium diet that promotes acidic urine
treat UTI

Question 16

how is struvite dissolution monitored?

Answer 16

urinalysis and imaging for 4-6 weeks
(USG <1.020 and reducing stone size)

Question 17

how can we prevent struvite?

Answer 17

prevent UTIs - treat infections when they arise
(don’t need lifelong dietary change)

Question 18

what pH does calcium oxalate form in?

Answer 18

neutral/acidic

Question 19

what is a predisposition for calcium oxalate formation?

Answer 19

hypercalcaemia

Question 20

can calcium oxalate be seen on radiography?

Answer 20

no - radiolucent

Question 21

are calcium oxalate more common in males/females?

Answer 21

males

Question 22

how are calcium oxalate uroliths treated?

Answer 22

remove them physically

Question 23

do calcium oxalate crystals recur?

Answer 23

yes (most will come back)

Question 24

how can calcium oxalate uroliths be prevented?

Answer 24

prevent predispositions - hypercalcaemia, metabolic acidosis, vitamin D excess
increase urine output - decrease concentration of urine

Question 25

what are urate crystals associated with

Answer 25

certain breeds (Dalmatian)
portosystemic shunts

Question 26

what pH do urates form at?

Answer 26

acidic

Question 27

can urates be seen on radiography?

Answer 27

no - radiolucent

Question 28

how can urate uroliths be treated?

Answer 28

low protein, purine, alkaline producing diet (medical dissolution)
continue this diet life long

Question 29

can cystine be seen on radiography?

Answer 29

no - radiolucent

Question 30

what predisposes a dog to cystine?

Answer 30

males (androgen linked)

Question 31

what uroliths can be treated medically?

Answer 31

struvite, urate, cystine