Urolithiasis Flashcards
What is the best resource on the planet for anything and everything Urolith?
Minnesota Urolith Center
What is the definition of Urolithiasis?
Term referring to the causes and effects of stones anywhere in the urinary tract. It is a sequelae of multiple underlying abnormalities
What is the pathophysiology of urolith formation?
- Precipitation of minerals to form crystals
- Crystals aggregate
- Stones form
When cats are blocked, is it a stone?
Hell no! It is a mucus crystalline plug. Usually from feline idiopathic cystitis.
What does crystalluria mean?
It does not mean urolithiasis and may not be associated with stone formation.
May be harmless and an in vitro phenomenon
Can be helpful to monitor or for diagnosis
What is a nidus?
An area of obvious initiation of urolith growth
What is the definition of the stone of a urolith?
The major body of the urolith that surrounds the nidus
What is the definition of a shell?
The outer precipitated material that surrounds the “stone” portion of the urolith
How can a stone be classified as a certain material?
It must be >70% of a single type of material, otherwise it is classified as mixed
What are clinical signs of urolithiasis?
Lower urinary tract
- Dysuria
- Hematuria
- Inappropriate urination
- Pollakiuria
Explain nephrolithiasis and it’s prevalence
It is an upper urinary tract urolith that can occur with lower urinary tract uroliths.
Be aware they may be present and imaging to evaluate the whole urinary tract is indicated.
They are rare (3%) and females are more affected than males.
What are diagnostic tools for urolithiasis?
Radiographs and ultrasound. There are pros and cons to each and each can pick up something the other can’t
Urate crystals are not seen on radiographs (not radio dense) but will be seen on ultrasound
Air and contrast material may help detect radiolucent stones
What is the only way to definitively determine stone type?
Analysis. Other tests like radiographs, Urine pH, statistical data only guide
What are some things a urolith could decide to do?
Spontaneously pass, dissolve, become inactive, do nothing, contribute to a UTI, or obstruct. Many options!
What are some canine urolith types?
- Struvite (Mg ammonium phosphate)
- Calcium oxalate
-95% are these first two - Urate - Dalmatians
- Cystine
- Silica
- Calcium phosphate carbonate
Canine struvite (Mg ammonium phosphate) uroliths
Common findings that can may or may not be pathologic. Can be a consequence of a UTI (Females > Males).
Exist in neutral to alkaline urine and are moderately radiopaque.
Canine calcium oxalate uroliths
Are common but hypercalcemia, hypercalciuria, and urine supersaturation are risk factors. Also may be a gene mutation.
Can look like anything, acidic to neutral urine, and are radiopaque.
How do you manage canine calcium oxalate uroliths?
These will not dissolve, only struvites will.
1.Check a chem panel for calcium and kidney values
2. Medical management to increase urine pH to >6.5 and USG <1.020
-A diet to help with less acidic urine, potassium citrate to increase pH, and a canned diet for increased water consumption
3. Surgery
Likely to recur
Canine Urate uroliths
Only common in Dalmatians, among other breeds (genetic mutations) and can be a marker for portosystemic shunts.
Radiolucent to mildly opaque in acidic to neutral urine
How do you manage canine urate uroliths?
- Check a chem panel and bile acids for liver function. Manage liver if appropriate.
- Give a low purine/protein diet with increased water intake
- Allopurinol if diet changes are not effective?
Have you reviewed the pictures of the different crystals?
Yes: Look at you go
No: Honestly, what are you doing with your life?
Canine cystine uroliths
Cystinuria is a genetic defect where cystine is not absorbed in the tubules.
Occurs in acidic to neutral urine and are Radiolucent
Uncommon but highly recurrent (2 weeks later) in males > females
How do you manage canine cystine uroliths?
- If intact male, castrate
- Diet therapy
- Thiola (Tiopronin)?
- If neutered male, they need a perineal urethrostomy (PU) to re-route the urine to come out near anus like a female
Canine silica uroliths
Associated with dietary corn gluten feed or grain hulls ingredients
Uncommon but males more than females
Acidic urine and highly radiopaque
How do you manage canine silica uroliths?
Diet change, high moisture foods, and pica elimination
Feline urolith types
Stones are uncommon and blockages are RARE in cats. It is usually due to a mucus crystalline plug
- Struvites
- Calcium oxalate
- Calcium phosphate
- Ammonium urate
Feline struvite uroliths
Common in the bladder in cats 2-10 years old
Culture the urine but it’ll be sterile usually
Diet therapy for struvite elimination and increased water consumption
Likely they will dissolve with proper management and should be attempted first if not blocked
What does “I don’t C U” stand for?
C: Cysteine
U: Urate
Are not seen on radiographs but yes on ultrasound
Feline calcium oxalate uroliths
A. Common enough
B. Risk factors include hypercalcemia (feline idiopathic hypercalcemia) and hypercalciuria
C. Causation not known
D. Radiopaque in acidic urine
Increase water intake and avoid hypersaturation
Feline calcium phosphate uroliths
Uncommon and radiopaque
Alkaline to neutral urine
No protocol to dissolve or prevent CaP for cats
Increase water intake
Feline ammonium urate uroliths
Uncommon
Rarely associated with portovascular anomalies
Acid urine and radiolucent
Increase water consumption
What is lithotripsy?
Using high energy shock waves to crush or fragment uroliths
Done only at specialty centers
What are some good tips for diagnosing and managing urolithiasis?
- Try to predict urolith type based on pH, imaging, and microscope evaluation
- Culture the urine before ABX
- Increase water consumption
- Re-check!
- Be careful with diets
- Treat if clinical, monitor if not
Send them to the Minnesota urolith lab, the second happiest place on earth
