Urolithiasis

Question 1

What are the main canine bladder stones?

Answer 1

• Struvite
• Calcium oxalate dihydrate
• Purine
• Cysteine
• Urate

Question 2

How are uroliths diagnosed?

Answer 2

• History
• Clinical signs
• Physical exam
• Imaging

Question 3

What is the pH of most uroliths? What is the exception?

Answer 3

• Most uroliths = acidic
• Struvite = alkaline (+calcium phosphate)

Question 4

What uroliths can + can’t be treated by medical dissolution?

Answer 4

• Can be treated =
  -Struvite
  -Urate
  -Cysteine
• Can’t be treated =
  -Oxalate
  -Silicate
  -Phosphate

Question 5

What is voiding urohydropulsion? What size of uroliths can be retrieved?

Answer 5

• Pass catheter + pump water into bladder = express bladder holding dog so that trigone is pointing ventrally
• 1-3mm in male dogs
• up to 10mm in female dogs

Question 6

What are struvites? What can predispose?

Answer 6

• Magnesium ammonium phosphate hexahydrate
• UTI predisposes
• Females > males
• Lower UT > UUT
• Miniature Schnauzer, shitzhu, bichon frise, miniature poodle, cocker spaniel, Lhasa apso

Question 7

How can you dissolve struvites?

Answer 7

• Treat UTI
• Feed diet low in protein, phosphorus + magnesium = promoting acidic urine

Question 8

How can you monitor struvite dissolution?

Answer 8

• Urinalysis + imaging every 4-6wks
  -USG <1.020 + 20% reduction in stone size
  (takes around 3 months to resolve)

Question 9

What predisposes dogs to calcium oxalate crystals?

Answer 9

• Hypercalcaemia
• Males > Females
• Toy breeds
• Older dogs

Question 10

What is Tx of calcium oxalate uroliths?

Answer 10

• Must be physically removed
• Recurrent (50% recurrence in 2 years)

Question 11

How can you prevent calcium oxalate uroliths?

Answer 11

• Rule out hypercalcaemia, metabolic acidosis, vitamin D excess
• Increase urine volume = increasing voiding frequency
• Wet diets

Question 12

What are predisposed to urate stones?

Answer 12

• Dalmatian, English bulldogs
• Dogs that get PSS - yorkshire terriers, miniature schnauzer
• Males > Female
• UTIs + high protein also predisposes

Question 13

How do you manage urate stones in dogs without liver disease?

Answer 13

• Diet = low protein, purine + produce alkaline urine
  -can alkalinise urine with sodium bicarbonate in diet

Question 14

How can you prevent recurrence of urate stones?

Answer 14

• Feed low purine diet - check urine pH, SG, BUN, sediment
• Drugs = allopurinol

Question 15

What predisposes cysteine crystals?

Answer 15

• Male > Female
• Daschunds
• May be sexed link - neuter male dogs?