Nutritional Management Of Urolithiasis Flashcards
What forms uroliths?
Uroliths form with sustained alterations in urine that promote supersaturation of certain compounds.
Once crystals form they can become stones.
What possible factors are involved in urolith formation?
PH, mineral concentration of urine, inhibitors and promoters of urolith formation.
What are the signs of uroliths?
Some are asymptomatic
Lower urinary signs including, urinary incontinence, hematuria, dysuria, pollakiuria, periuria, stranguria.
Can cause urinary obstruction.
What are the common uroliths?Less common?
Struvite and calcium oxalate (cats calcium oxalate) dogs (struvite)
Urate, cystine, silicate, ect
Who is not likely to have stones?
Young animals
What is
Hematuria, pollakiuria, stranguria, periuria?
Hematuria- blood in urine
Pollakiuria- often urination (more incidences of urination)
Stranguria - painful or strenuous urination
Periuria- urination in inappropriate location.
How do you diagnose stones?
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
What is relative supersaturation?
- 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
How can you prevent urolithiasis?
- urine dilution
- precursor excretion
- urine composition/ environment modification (add inhibitors/ change ph)
How can you dissolve stones?
Struvite, urate, cystine
- Via nutritional/ medical therapy
How can you dilute urine to prevent stones?
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.
How can you change dietary precursors?
Struvite- combination of ammonia and phosphate-> diet with less of these Precursors would be ideal
- in struvite acidify urine
What causes struvites?
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
What are the predisposition for struvites?
- 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?
How can you achieve dissolution of struvites?
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)
How can you prevent struvites in?
Infection specific strategies
- Address uti’s
- Continue monitoring
- Address predisposition
- Cranberry extract does not work
- Urine dilution
- precursor intake
What urine concentration should we be shooting for in dogs and cats when diluting their urine? How much is our initial moisture intake goal.
- 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.
What is the role in FIC as components of urethral plugs?
FIC cats you may want to put them on a diet that is preventative
What are calcium oxalate?
- Oxalates typically come from plants
- some can be formed by compounds in the body.
- Non soluable cystals in water
What breeds have predispositions (dogs) that have calcium oxalates?
- miniture schnauzer, lasapzo ,……***
What are calcium oxalate predispositions?
Hypercalcemia (Cancer, hyperparathyroidism, ect)
Increased absorption of calcium and oxalate
Increased excretion of calcium and oxalate excretion is ideal.
What are the desired characteristics for diets when it comes to calcium oxalate predisposition
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
What is the potential predispositions in cats for calcium oxalate?
Neutered male
Older adults
Persian, himalayin
Upper urinary ( usually nephroliths are calcium oxalate )
Can you dissolve calcium oxalate?
No you cannot in dogs or cats
What are dietary prevention strategies for calcium oxalates?
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.
What should you avoid in term of components of treats to prevent Calcium oxalates?
Increased vitamin C
Increased Calcium
Includes glycine
How long can you feed SD?
Deficient in protein, no longer than 3 months.
What is the cause of urate urolithiasis?
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
How can you dissolve urate urolithiasis?
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.
Are there genetic tests for urolithiasis?
Yes, and there a may be some benefit to putting them on a diet that prevents urates.
What else can treat leishmaniasis?
Allopurinol
What is the mechanism of allopurinol and how it prevents urate stone formation?
Xanthine oxidase is inhibited by allopurinol -> so it prevents stones, but it can cause xanthine stones ( if given too much)
What are cystine urolitiasis?
Cystine is disulfide AA
- Normally reabsorbed in the PCT, therefore genetic defect in the reabsorption mechanism is responsible.
What are strategies to work on dissolution of cystine urolithiasis?
- 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)
What are diet options for pets with cystine urolithiasis?
Commercial ( Vegetarian diet RC or Urinary UC ( low in Cystine as well as purine) Home cooked ( custom formulated)
What is the issue with eliminating/ reducing cystine and methionine? How can you prevent issues?
The issue is that these are essential for taurine synthesis. You can supplement taurine if you are concerned there is not enough.
What are the other crystals that can be found in the urine? What is the treatment for them?
Crystals: Silicate, calcium phosphate/ brushite, calcium carbonate.
- Dilution is the solution, limiting intake of urolith components.
