Canine and Feline Urolithiasis. Magnesium ammonium phosphate Calcium oxalate Urate Cystine Calcium phosphate Silicate Mixed stones

Canine and Feline Urolithiasis


Magnesium ammonium phosphateCalcium oxalateUrateCystineCalcium phosphateSilicateMixed stones

Canine UrolithiasisPrevalence (%)

1986 1990 1994Struvite 67.0 57.0 49.5Calcium oxalate 6.8 19.8 32.7Urate 5.1 5.5 8.0Cystine 2.4 1.6 1.0Calcium phosphate 3.0 1.6 0.6Mixed/Compound 11.9 12.6 7.4

Feline Urolithiasis Prevalence (%)

1986 1990 1996Struvite 85.0 66.0 36.4Calcium oxalate 3.0 16.0 53.4Urate 1.8 6.1 4.9Cystine 0.0 0.1 0.1Calcium phosphate 2.0 2.9 0.6Mixed/compound 5.2 5.9 3.4

Canine and Feline UrolithiasisPathogenesis

Concentration of building blocksUrinary pHTime


labile region

critical supersaturation

metastabile supersaturation

saturation, Ksp

undersaturation

increasingactivityproduct


Activity ProductConcentration of crystal constituentsConcentration of other solutesUrine pHIonic strength

Feline Lower Urinary Tract DiseasePathogenesis

UrolithsUrethral plugs

Large quantity of matrix ( > 50% matrix)Mixed with crystals or without crystals

Canine and Feline UrolithiasisClinical Diagnosis

AgeGenderBreedRadiograhic findings CrystalluriaUrinary pHPresence of infection


Urinary pH Alkaline

Struvite

Calcium apatite

Acid to neutral

Calcium oxalate

Cystine


Presence of Infection

Urease producing micro-organisms

Struvite Dogs most cases UTI Cats 1-2% UTI

Canine UrolithiasisUrease producing bacteria

2NH3 + CO2 NH2 =C=NH2 + H2O

O

=

Urease

NH4++ HCO3-NH3

+ H2O + CO2

Canine and Feline UrolithiasisTreatment & Prevention

TreatmentDietary & Medical dissolutionSurgicalNon-surgical retrieval

Prevention of recurrenceDietary modificationsWater intake

Canine and Feline UrolithiasisDietary management

Undersaturate the urineExcretion of building blocks

Urine volume

Urinary pH favorable to stone dissolution

Feline Lower Urinary Tract DiseaseStruvite & calcium oxalate

No single diet for both struvite and calcium oxalate

Conflicting actions of several key nutrients

Clinical diagnosis is essential


Struvite Ca Oxalate

pH

Mg

PO4

Na

Lower Urinary Tract Disease

Feline Lower Urinary Tract DiseaseStruvite

Patient profileFemale Younger cat, < 7 yearsObeseIndoor, multi-cat householdLow water intakeMore alkaline urinary pH (> 6.5)

Feline Lower Urinary Tract DiseaseCalcium oxalate

Patient profileMale (neutered)Older cat > 4 years ObesePersian, Himalayan, BurmeseIndoor, urbanMore acid urinary pH

Feline Lower Urinary Tract Disease Calcium oxalate

Medical historyHistory of calcium oxalate, documented

by quantitative urolith analysisNo response to appropriate dietary struvite

therapy Inappropriate use of urinary acidifiers


Treatment

SurgeryPrevention

Avoid dietary and medical risk factors


Dietary risk factors Excess vitamin C & D Acidification Ad libitum feeding Moderate protein = protective Very low protein = risk factor Low fiber Feeding dry Excessive Ca & P restriction

Feline Lower Urinary Tract DiseaseCalcium oxalate

Nutrient profilePotassium citrateUrinary pH 6.6-6.8Increased moisturePyridoxine (vitamin B6)Soluble fiberModerate magnesium

Feline Lower Urinary Tract Disease Struvite

Mg - NH4 - PO4 . 6H20

MagnesiumAmmoniumAnionic phosphate


Dietary managementReduced magnesium

Less than 20 mg/100 kcal ME

Less than 0.1% (dry matter) Increased diuresis

Water

Sodium


Dietary managementAcid urine pHAvoid over-acidification

Metabolic acidosis

Renal diseaseDissolution - urinary pH 5.9 - 6.1Prevention - normal acid urinary pH 6.2-6.4

Canine and Feline UrolithiasisUrinary acidification

Decrease in urine pH from 8.5 to 5.5 NH4+ - 1000 x Increase

PO4 3 - - 13 000 x decrease

Moderately acid urine pH : 6.2 - 6.4

Contra-indicaties voor verzurend dieet

• Nierinsufficiëntie

• Groei (ontkalking)

• Acidose

• Ca-oxalaat stenen

• Urineverzuurders toevoegen aan verzurend dieet


Dietary managementFeed calculolytic diet exclusively1 - 2 monthsLonger if UTI is present If no reduction of calculi after 2 months,

surgery should be considered

Canine UrolithiasisStruvite

Mg - NH4 - PO4 . 6H20

Crystal DietMagnesium MagnesiumAmmonium ProteinAnionic phosphate Phosphorus

Canine UrolithiasisStruvite - Dissolution

NutrientsMinimize proteinReduce magnesiumReduce phosphorusStimulate water intakeIncrease sodium

Acidify urine


% DM Normal Calculolytic Foods

DietProtein 15 - 60 7.6Magnesium 0.03 - 0.27 0.02Phosphorus 0.41 - 2.43 0.10Sodium 0.11 - 2.22 1.28Urinary pH 6.7 - 8.3 5.9 - 6.1


Feed calculolytic diet exclusivelyTreat urinary tract infectionContinue treatment till 4 weeks after

radiographic dissolution


Monthly evaluation Radiography Serum urea nitrogen (SUN) Urinalysis: crystals, culture bacteria

Owner compliance Struvite crystalluria SUN > 10 mg/dl


Reasons for failureInsufficient timeNon-compliance by ownerUrinary tract infectionNon-Struvite urolith

Canine UrolithiasisStruvite - Treatment

Indications for surgeryObstructionAnatomical defectsNo response to medical treatmentDiet is contraindicated

Canine UrolithiasisStruvite - Treatment

Diet contra-indicationsSodium retention

Heart failure, hypertension, liver disease, nephrotic syndrome

Increased protein requirements

Pregnancy, lactation, growth, cats

Acidifing dietRenal insuff., metabolic acidosis, growth, Ca-ox.

Canine UrolithiasisStruvite - Prevention

Prevention of recurrenceUrinary acidificationModerate reduction of protein, Mg, PModerate sodium level

Canine UrolithiasisCalcium oxalate

Treatment SurgeryHydropropulsion


Verminderen uitscheiding bouwstenen• CalciumCa-opname + CalciurieVitamine D3: Ca aborptie + indirect calciurieP: te laag: stimulatie Vit D3Na: stimulatie calciurieZure urine: stimulatie calciurie

• Oxalaat: spinazie, rubarber, chocolade


Verhogen inhibitoren• Magnesium• pH urine:Alkalinserend: vb. K-citraatDierlijke eiwitten verzuren: hoge eiwitopname

vermijden

Andere: wateropname

Canine UrolithiasisCalcium oxalate - Prevention

Prevention of recurrenceAvoid excessive intake of proteinLow calcium intakeLow oxalate intakeLow sodium intakeAvoid urinary acidificationPotassium citrate


Prevention of recurrenceAdvanced renal failure diet

Canine Urolithiasis Ammonium urate - Treatment

DissolutionDietary managementAllopurinolUrinary tract infection

Canine UrolithiasisAmmonium urate - Treatment

Allantoin

Meat diets Xanthine

Uric acid

Uricase

(Defect in Dalmatians)

Xanthine oxidase

Allopurinol

+

+

Purine / Pyrimidine

(Nucleic acids &

Cell nuclei)


Dietary managementAmmonium - Low protein Urate - Low purine

Muscle & organ tissue = high in purines

Egg & casein = low in purines

Alkalinize urine

Canine UrolithiasisAlkalinize urine

NH3NH4+

H+

Decreases NH4+ concentration


Advanced renal failure diet8 - 11 weeks required for dissolutionMonitor for urethral obstruction

Canine UrolithiasisAmmonium urate - Prevention

Prevention of recurrenceAdvanced renal failure diet

Low in protein & purines

Alkalinizing the urine

Allopurinol

Canine Urolithiasis Cystine - Composition = Cysteïne - Cysteïne

Genetische afwijking: gestoorde reabsorptie van

Cystine: weinig oplosbaarOrnithineLysine wateroplosbaarAlanine

Canine Urolithiasis Cystine - Treatment

Surgery

Dissolution


DissolutionDietary managementD-Penicillamine2-MPG (Thiola)Urinary tract infection


Dietary managementLow Protein

Low in cystine, cysteine

Low sodiumAlkalinize urineAdvanced renal failure diet


DissolutionCystine + D-Penicillamine or 2-MPG

D-Penicillamine-Cysteine

2-MPG - Cysteine

Solubility x 50


Urine pH

Solubility Urine pH

1.0 x 7.0

1.3 x 7.5

2.0 x 8.0

Canine Urolithiasis Cystine - Prevention

Prevention of recurrenceInborn error do not breedAdvanced renal failure diet2-MPG 15 mg/kg BID

orD-Penicillamine 10 mg/kg BID

Gemengde stenen

Ca-oxalaat & struviet Primair vs. secundair

irritatie - ontsteking

Ca-oxalaat

secundaire infectie

ureasevorming

pH & NH4+

Struvite

Canine and Feline UrolithiasisConclusionCorrect differential diagnosis is

important for success of treatmentUrolithiasis has an underlying cause

which should be further investigatedDietary versus surgical treatment is

decided based on stone type, location and medical factors.

Canine and Feline UrolithiasisConclusionOne diet can not work for all types of

urolithsPreventive diets should provide balanced

nutritionAvoid over-acidification of the urine

Documents

Canine and Feline Urolithiasis. Magnesium ammonium phosphate Calcium oxalate Urate Cystine Calcium phosphate Silicate Mixed stones