Urolithiasis Flashcards
where do uroliths tend to occur in dogs and cats
normally lower urinary tract, i.e. bladder & urethra
what are struvite uroliths made of
Magnesium ammonium phosphate
what are struvite uroliths associated with in dogs
Usually associated with UTIs caused by urease producing bacteria
are males or females more prone to struvite uroliths
females
likely due to increased tendency of female dogs to develop UTIs
list the risk factors of struvite uroliths in dogs
abnormal retention of urine
Any condition that predisposes to UTI - e.g. diabetes mellitus, cushings
susceptible breeds- Miniature schnauzer, Shih Tzu, Bichon
what are struvite uroliths associated with in cats
90% are sterile – in contrast to dogs (infection-induced seen predominantly in cats > 10 yrs)
what are the risk factors of struvite uroliths in cats
abnormal retention of urine
formation of concentrated urine - moisture content of food, water intake
Urine-alkanising metabolites in diets
list the risk factors for formation of calcium oxalate uroliths
acidifying diets
Oral calcium supplements given outside of mealtimes
Excessive dietary protein
Formation of concentrated urine
what are urate uroliths made of
Composed of uric acid, sodium urate or ammonium urate
how are urate uroliths formed
Impaired conversion of uric acid to allantoin ——-> increased concentration of uric acid in serum and urine.
what breeds are predisposed to urate uroliths
Dalmations and Black Russian terriers
which urolith is associated with porto systemic shunt
urate
list 2 risk factors of urate uroliths
High Purine intake (glandular meat)
Persistent aciduria in a predisposed animal
how do cysteine uroliths form
inborn error of metabolism caused by defective tubular resorption of cysteine and other amino acids
which dogs are more affected by cysteine uroliths
Predominantly intact male dogs affected
list 3 risk factors of cysteine uroliths
Genetic predisposition to cystinuria
Acidic, concentrated urine
Urine retention
how do xanthine uroliths form
Impaired Xanthine oxidase activity leads to hyperxanthinaemia and xanthinuria
Familial or congenital defect e.g. CKCS
list 4 risk factors of xanthine uroliths
Genetic predisposition
Acid urine, highly concentrated urine
Urine retention
Allopurinol treatment
list 2 risk factors of calcium phosphate uroliths
Excessive dietary calcium, primary hyperparathyroidism
UTI – with urease producing bacteria
List the clinical signs of urolithiasis
lower urinary tract signs- dysuria, haematuria, pollakiuria
+/- signs of urinary obstruction
urate- signs of PSS
Not that specific
Describe how urinalysis can help diagnose uroliths
Not really
pH useful- clue to urolith type - helps monitor dietary management later on
rules out UTI
crystals can be misleading
What is most helpful when diagnosing uroliths
imaging key
radiography or ultrasound
list the uroliths that are radiopaque
calcium oxalate
struvite
calcium phosphate
list the uroliths that are radiolucent
Xanthine
need contrast to see
what do struvite uroliths look like
usually round/faceted
appear smooth
what do calcium oxalate uroliths look like
irregular shape
Why does it matter that we know what type of urolith it is?
A diagnosis of urolithiasis without knowing the composition makes it impossible to select effective management.
what do you see on ultrasound with uroliths
acoustic shadowing
Remember gravity when deciding if mass or urolith
why can ultrasound be better than radiography when diagnosing uroliths
can be done conscious
will pick up radiolucent uroliths
describe medical treatment of uroliths
analgesia- usually NSAID
antibiotic if concurrent UTI - generally prolonged course if struvite (C and S)
What is a specific urolith treatment for urate
allopurinol - Xanthine Oxidase inhibitor – for dissolution – takes at least 4-6 weeks, sometimes required long term
not effective if PSS
what diet is used to dissolution calcium oxalate uroliths
Not amenable to dissolution (dietary management is for prevention of recurrence)
what diet is used to dissolution struvite uroliths
Prescription struvite dissolution diet (acidifying)
what diet is used to dissolution urate uroliths
Low-purine, alkalinising diet (contraindicated if pregnant/lactating)
what diet is used to dissolution cysteine uroliths
Alkanising, lower methionine protein content
what diet is used to dissolution calcium phosphate uroliths
Not amenable to dissolution
what diet is used to dissolution xanthine uroliths
Low purine, alkalinising
which uroliths need surgical removal
Calcium Oxalate
Calcium phosphate
larger Struvite uroliths - depends on the dog and their clinical signs
if a animal is blocked with urolith what is a surgical option
try and push urolith(s) back into bladder by retrograde urohydropulsion
what do you need to warn owners about post op after urolith surgical removal
warn owner of likely haematuria
need to monitor urine output
watch for dysuria
Describe how to prevent calcium oxalate uroliths recurrance
High moisture alkalinising diet – but monitor for Struvite crystalluria
Monitor – monthly urinalysis, aim for SG < 1.020 (dogs) & < 1.030 (cats) and pH >6.5
Correct any hypercalcaemia
Describe how to prevent struvite uroliths recurrance
High moisture acidifying diet – but care re CaOx crystalluria
Monitor urine pH & SG (as for CaOx but want pH < 7
Ensure UTI fully resolved – repeat C & S at end of antibiotic course
Describe how to prevent urate uroliths recurrance
High moisture alkalinising diet
Some dogs require long term Allopurinol
Describe how to prevent cysteine uroliths recurrance
High moisture alkalinising diet
Dogs – consider castration, will reduce recurrence if have sex-linked genetic predisposition
Describe how to prevent calcium phosphate uroliths recurrence
High moisture diet; senior diets may be useful due to lower protein
Describe how to prevent xanthine uroliths recurrence
High moisture alkalinising diet
