Nutritional Management Of Urolithiasis

Question 1

What forms uroliths?

Answer 1

Uroliths form with sustained alterations in urine that promote supersaturation of certain compounds.
Once crystals form they can become stones.

Question 2

What possible factors are involved in urolith formation?

Answer 2

PH, mineral concentration of urine, inhibitors and promoters of urolith formation.

Question 3

What are the signs of uroliths?

Answer 3

Some are asymptomatic
Lower urinary signs including, urinary incontinence, hematuria, dysuria, pollakiuria, periuria, stranguria.
Can cause urinary obstruction.

Question 4

What are the common uroliths?Less common?

Answer 4

Struvite and calcium oxalate (cats calcium oxalate) dogs (struvite)

Urate, cystine, silicate, ect

Question 5

Who is not likely to have stones?

Answer 5

Young animals

Question 6

What is
Hematuria, pollakiuria, stranguria, periuria?

Answer 6

Hematuria- blood in urine
Pollakiuria- often urination (more incidences of urination)
Stranguria - painful or strenuous urination
Periuria- urination in inappropriate location.

Question 7

How do you diagnose stones?

Answer 7

Crystalluria- be careful with over interpreting ( sometimes there is crystals that form when urine sits around, also you may not have an issue with certain small amounts of crystals )
Ultrasound - shadowing, sand, grit, etc.
Radiographs -not all uroliths are radiopaque
- Struvite and calcium oxalate are radiopaque
- Urate, xanthine, cystine are not (often)
Contrast radiographs
Urolith mineral analysis

Question 8

What is relative supersaturation?

Answer 8

• Computer technique
• precipitate vs. Stay in solution
  Based on thermodynamic behavior
• concentration of solute compound
• ph
• temp
  -interaction with other compounds
  Supersaturated: high risk
  Meta stable: possible
  Unsaturated: unlikely to form

Question 9

How can you prevent urolithiasis?

Answer 9

• urine dilution
• precursor excretion
• urine composition/ environment modification (add inhibitors/ change ph)

Question 10

How can you dissolve stones?

Answer 10

Struvite, urate, cystine
- Via nutritional/ medical therapy

Question 11

How can you dilute urine to prevent stones?

Answer 11

Increase water intake: Add water fountains, higher sodium diets, wet food, protein content decrease.
Protein is metabolized to urea, which is concentrated in renal medulla. Low protein = medullary washout. Urine doesnt get as concentrated.

Question 12

How can you change dietary precursors?

Answer 12

Struvite- combination of ammonia and phosphate-> diet with less of these Precursors would be ideal
- in struvite acidify urine

Question 13

What causes struvites?

Answer 13

UTI (dogs)
Urease producers
- Staphylococcus , proteus, klebsiella
Can be sterile ( cats)
Ammonia pushes pH up, which pushes urine towards supersaturated range.
Ammonium is also a component of struvite, so this can increase cause

Question 14

What are the predisposition for struvites?

Answer 14

• Obesity (more skin folds/ micro environment, tend to empty bladder less, higher risk of compounds precipitate.
• Sex (more common in females, proximity between anus and vulva)
• Anatomical (hooded vulva)
• Endocrinopathy (diabetes Mellitus, Cushings, glucosuria,
• Immunosuppression
• Dermatological disease
  Anything that predisposes to UTI
  Cats: unsure why?

Question 15

How can you achieve dissolution of struvites?

Answer 15

Medical management
- treat UTI
- treat predispositions
Diet strategies
- dilution
- Precursors
- composition
Monitoring
- culture
- imaging ( you should see rather quick decrease in size of urolith)
- failure (make sure were successful or know if we are not)

Question 16

How can you prevent struvites in?

Answer 16

Infection specific strategies

• Address uti’s
• Continue monitoring
• Address predisposition
• Cranberry extract does not work
• Urine dilution
• precursor intake

Question 17

What urine concentration should we be shooting for in dogs and cats when diluting their urine? How much is our initial moisture intake goal.

Answer 17

• Dog < 1.020
• Cat < 1.025
  Goal: 85%

Monitor serial USG at home ( with strips/ refractometer)
Can mix can food 1:1 with H2O or 1:5 H2O with dry food.

Question 18

What is the role in FIC as components of urethral plugs?

Answer 18

FIC cats you may want to put them on a diet that is preventative

Question 19

What are calcium oxalate?

Answer 19

• Oxalates typically come from plants
• some can be formed by compounds in the body.
• Non soluable cystals in water

Question 20

What breeds have predispositions (dogs) that have calcium oxalates?

Answer 20

• miniture schnauzer, lasapzo ,……***

Question 21

What are calcium oxalate predispositions?

Answer 21

Hypercalcemia (Cancer, hyperparathyroidism, ect)
Increased absorption of calcium and oxalate
Increased excretion of calcium and oxalate excretion is ideal.

Question 22

What are the desired characteristics for diets when it comes to calcium oxalate predisposition

Answer 22

Calcium -> moderate
Phosphorus -> moderate ( to bind some of the calcium/ good Ca++/Phos balance)
Vitamin D: moderate (not enough for Toxicity / not too low)
Oxalate: lower/ reduced
Vitamin C -> should not be high, can be metabolized to oxalate
Vit B6 should also be limited because they can form oxalates as well

Question 23

What is the potential predispositions in cats for calcium oxalate?

Answer 23

Neutered male
Older adults
Persian, himalayin
Upper urinary ( usually nephroliths are calcium oxalate )

Question 24

Can you dissolve calcium oxalate?

Answer 24

No you cannot in dogs or cats

Question 25

What are dietary prevention strategies for calcium oxalates?

Answer 25

Moistures
Precursors
- balanced diet ( moderate calcium)
- Low oxalate intake
- investigate supplements and treats ( some can contribute/ be very important sources of oxalate)
Conditions: ideally don’t acidify the urine ( too acidic will promote ca++ oxalates.

Question 26

What should you avoid in term of components of treats to prevent Calcium oxalates?

Answer 26

Increased vitamin C
Increased Calcium
Includes glycine

Question 27

How long can you feed SD?

Answer 27

Deficient in protein, no longer than 3 months.

Question 28

What is the cause of urate urolithiasis?

Answer 28

Breed dispositions -> genetic abnormalities
Problems with purine metabolism ( Nucleic acid)
- Dalmatians, English bull dogs, Yorkies, others
- Siamese, Egyptian may
Liver disease
- decreased conversion of urine acid to Allintoin

Question 29

How can you dissolve urate urolithiasis?

Answer 29

Urinary dissolution
dec precursors ( decrease purine consumption, avoid high purine foods (liver, organ meats, ect), use low purine foods ( dairy, egg, some vegetable based)
Make urine more alkaline
- accomplished with reduced protein/ vegetarian diet
Dissolution protocols: only successful with non- liver disease urate
- allopurinol: be careful of inducing xanthine uroliths.

Question 30

Are there genetic tests for urolithiasis?

Answer 30

Yes, and there a may be some benefit to putting them on a diet that prevents urates.

Question 31

What else can treat leishmaniasis?

Answer 31

Allopurinol

Question 32

What is the mechanism of allopurinol and how it prevents urate stone formation?

Answer 32

Xanthine oxidase is inhibited by allopurinol -> so it prevents stones, but it can cause xanthine stones ( if given too much)

Question 33

What are cystine urolitiasis?

Answer 33

Cystine is disulfide AA
- Normally reabsorbed in the PCT, therefore genetic defect in the reabsorption mechanism is responsible.

Question 34

What are strategies to work on dissolution of cystine urolithiasis?

Answer 34

• Urine alkalization
• 2- MPG (used)
• Urine dilution
• Potassium Citrate
• takes about 1-2 months
• prevention is very important
• Diet must be low in cysteine and methionine intake ( methionine converts to cystine)

Question 35

What are diet options for pets with cystine urolithiasis?

Answer 35

Commercial ( Vegetarian diet RC or Urinary UC ( low in Cystine as well as purine) 
Home cooked ( custom formulated)

Question 36

What is the issue with eliminating/ reducing cystine and methionine? How can you prevent issues?

Answer 36

The issue is that these are essential for taurine synthesis. You can supplement taurine if you are concerned there is not enough.

Question 37

What are the other crystals that can be found in the urine? What is the treatment for them?

Answer 37

Crystals: Silicate, calcium phosphate/ brushite, calcium carbonate.
- Dilution is the solution, limiting intake of urolith components.