Urolithiasis

Question 1

Which type of urolith forms in:
Acidic urine?
Alkaline urine?

Answer 1

Acidic = cystine
Alkaline = struvite

Question 2

Which 2 types of uroliths do UTIs predispose to?

Answer 2

Struvite and Urate

Question 3

What is struvite?

How is it formed?

Answer 3

Magnesium ammonium phosphate
From magnesium and phosphorous in dietary protein
And urease-producing bacteria converting urea into ammonia (and bicarbonate)

Question 4

How does increased production of bicarbonate play a role in struvite formation?

Answer 4

Bicarbonate is formed from conversion of urea by urease-producing bacteria (also produces ammonia)
Bicarbonate increases the pH of urine, decreasing the solubility of struvite

Question 5

What is the signalment for struvite urolithiasis?

Answer 5

Female LUT

Miniature schnauzers, Shih Tzus, Bichon frises, minature poodles, cocker spaniels

Question 6

Which 3 types of uroliths are you able to visualise on radiographs?

Answer 6

1. Struvite
2. Calcium oxalate
3. Silicates

Question 7

What are 3 predisposing factors for calcium oxalate uroliths?

Answer 7

1. Hypercalcaemia
2. Increased dietary oxalate
3. Decreased citrate in urine

Question 8

What is the signalment for calcium oxalate urolithiasis?

Answer 8

Older male dogs

Similar breeds to struvite (+ Yorkshire terrier)

Question 9

What are two causes of ammonium biurate urolithiasis, and in which breeds?

Answer 9

1. Impaired hepatic transport of uric acid
   - Dalmatians and English Bulldogs
2. PSS (increased ammonium urates)
   - Yorkshire terrier and Minature Schauzer

Question 10

What type of urine is required for sediment examination?

Answer 10

FRESH!

Question 11

Which 3 types of urolith can be dissolved/dissoluted?

Answer 11

1. Struvite
2. Urate
3. Cystine

Question 12

Why would struvite dissolution fail?

Answer 12

Struvite outer layer, but calcium oxalate core

Question 13

Which type of urolith is associated with hyperparathyroidism?

Answer 13

Calcium phosphate

Question 14

Which type of urolith are GSDs, OES, Golden retrievers and Labradors predisposed to?
What can it be caused by?

Answer 14

Silicates
Diets high in corn gluten, soya bean hulls
Ingestion of soil

Question 15

What is the signalment for cystine uroliths?
What are they caused by?
What type of urine prediposes to them?

Answer 15

Males, Dachshunds (Bassets, English bulldogs)
Inherited disorder of renal tubular transport
Acidic

Question 16

What 2 things can be used to alkalinise urine?

Answer 16

Sodium bicarbonate

Potassium citrate

Question 17

What two drugs can be used for recurrent urate uroliths?

Answer 17

Allopurinol

Xanthine oxidase inhibitor (care, may predispose to insoluble xanthine stone formation if protein isn’t restricted)

Question 18

How long past radiographic resolution should you continue treatment of struvite urolithiasis?
What should you do regularly during treatment?

Answer 18

Continue 1 month past radiographic resolution

Check radiographs and urinalysis