CS: Urolithiasis Flashcards
CS - upper urinary tract uroliths
- variable
- haematuria
- CS compatible with acute kidney injury secondary to ureteral obstruction
Normal canine USG
1.015 - 1.045
Varies with fluid intake, hydration
Normal feline USG
1.035-1.060
Varies with fluid intake, hydration
What are the 2 most radioopaque crystals
calcium oxalate and struvit
What urine pH favours struvite and calcium oxalate formation?
- STRUVITE: alkaline
- CALCIUM OXALATE: acidic to neutral
T/F: uroliths >1cm likely to be struvite
True
T/F: sterile struvite uroliths rarely form in dogs
True - common in cats
Why do you need a stone sample?
detect what mineral type and whether different mineral layers are present.
What should you do if urine culture is negative in a dog with struvite uroliths?
the stone and/or bladder mucosa can also be cultured to be certain that a bacterial pathogen is not present
What is medical management of struvite sotnes?
dissolution and prevention of stone reformation (aim to reduce concentrations of ammonium, magnesium and phosphate in urine
Advantages - sx tx of struvite bladder stones
Most direct
Healing may commence say day
Disadvantages - sx tx of struvite bladder stones
Those inherent to sx (anaesthetic risk, post-op pain)
Risk of contaminating abdomen with infected urine
Incomplete removal nidus for recurrence
Bladder stitches not holding
Indications - sx removal of struvite bladder stones
- immediate/ emergency removal (e.g. blocked animal)
What is VUH?
= voiding urohydropulsion
- anaesthesia
- for small stones
- fill bladder via urinary catheter (sterile saline), agitating bladder so stones float freely in urine. Hold animal upright, remove catheter, then generating a high pressure urine stream to force stones out
What is cystoscopy?
- if stones small enough and avoiding sx is key
- cystoscope passed into bladder and stones retrieved with special basket (or fragmented via laser lithotripsy)
Advantages/ disadvantages of cystoscopy
o DISADVANTAGES: Special equipment, referral, generally more expensive than sx
o ADVANTAGES: recovery much faster
Outline medical management of struvite bladder stones
- dietary
o Uroliths should decrease in size within 3-4 weeks (if good owner compliance)
o Only feed until stone dissolved
o ABs needed as long as stones present in bladder (bacteria encrusted in stone and as stone dissolves they are released).
Reasons for tx failure when medically managing struvite bladder stones
- poor compliance with diet / ABs
- stone has layers of calcium phosphate in form of appatite or may not contain struvite
Disadvantages - medical management of struvite bladder stones
o DISADVANTAGES: long tx time, possibility of UT obstruction as stone gets smaller, v high in fat and salt and low in protein (not for patients with hx of pancreatitis, heart disease, kidney insufficiency or high BP)
CI - medical management of struvite bladders stones
urethroliths causing obstruction or if patient’s CS are severe.
Prevention - struvite stones
- high moisture diets
that produces a urine pH
What is a typical crystal appearance for ammonium urate?
‘thorn-apple’ appearance
Why is it often not possible to count the # of urate stones?
there are so many and range in size from grain of sand to ball bearing
How do you image a dalmation’s bladder after urate stone removal?
- ULTRASOUND as urate stones are radiolucent to faintly radioopaque so unlikely to be detected with radiography
