Canine and Feline Urolithiasis
Canine and Feline Urolithiasis
Magnesium ammonium phosphate
Calcium oxalate
Urate
Cystine
Calcium phosphate
Silicate
Mixed stones
Canine Urolithiasis
Prevalence (%)
 Struvite
 Calcium oxalate
 Urate
 Cystine
 Calcium phosphate
 Mixed/Compound
1986 1990
67.0 57.0
6.8 19.8
5.1
5.5
2.4
1.6
3.0
1.6
11.9 12.6
1994
49.5
32.7
8.0
1.0
0.6
7.4
Feline Urolithiasis
Prevalence (%)
 Struvite
 Calcium oxalate
 Urate
 Cystine
 Calcium phosphate
 Mixed/compound
1986
85.0
3.0
1.8
0.0
2.0
5.2
1990
66.0
16.0
6.1
0.1
2.9
5.9
1996
36.4
53.4
4.9
0.1
0.6
3.4
Canine and Feline Urolithiasis
Pathogenesis
Concentration of building blocks
Urinary pH
Time
Canine and Feline Urolithiasis
Pathogenesis
labile region
critical
supersaturation
metastabile
supersaturation
saturation, Ksp
undersaturation
increasing
activity
product
Canine and Feline Urolithiasis
Pathogenesis
Activity Product
Concentration of crystal constituents
Concentration of other solutes
Urine pH
Ionic strength
Feline Lower Urinary Tract Disease
Pathogenesis
Uroliths
Urethral plugs
 Large quantity of matrix ( > 50% matrix)
 Mixed with crystals or without crystals
Canine and Feline Urolithiasis
Clinical Diagnosis
Age
Gender
Breed
Radiograhic findings
Crystalluria
Urinary pH
Presence of infection
Canine and Feline Urolithiasis
Clinical Diagnosis
 Urinary pH
 Alkaline
Struvite
Calcium apatite
 Acid to neutral
Calcium oxalate
Cystine
Canine and Feline Urolithiasis
Clinical Diagnosis
Presence of Infection
Urease producing micro-organisms
Struvite
 Dogs most cases UTI
 Cats 1-2% UTI
Canine Urolithiasis
Urease producing bacteria
NH2 =C=NH2 + H2O
=
2NH3 + CO2
O
NH3 + H2O + CO2
Urease
NH4 + HCO3
+
Canine and Feline Urolithiasis
Treatment & Prevention
Treatment
Dietary & Medical dissolution
Surgical
Non-surgical retrieval
Prevention of recurrence
Dietary modifications
Water intake
Canine and Feline Urolithiasis
Dietary management
Undersaturate the urine
Excretion of building blocks
Urine volume
Urinary pH favorable to stone
dissolution
Feline Lower Urinary Tract Disease
Struvite & calcium oxalate
No single diet for both struvite and
calcium oxalate
Conflicting actions of several key
nutrients
Clinical diagnosis is essential
Canine and Feline Urolithiasis
pH
Mg
PO4
Na
Lower Urinary Tract Disease
Struvite
Ca Oxalate
Feline Lower Urinary Tract Disease
Struvite
Patient profile
Female
Younger cat, < 7 years
Obese
Indoor, multi-cat household
Low water intake
More alkaline urinary pH (> 6.5)
Feline Lower Urinary Tract Disease
Calcium oxalate
Patient profile
Male (neutered)
Older cat > 4 years
Obese
Persian, Himalayan, Burmese
Indoor, urban
More acid urinary pH
Feline Lower Urinary Tract Disease
Calcium oxalate
Medical history
 History of calcium oxalate, documented
by quantitative urolith analysis
 No response to appropriate dietary struvite
therapy
 Inappropriate use of urinary acidifiers
Feline Lower Urinary Tract Disease
Calcium oxalate
Treatment
Surgery
Prevention
Avoid dietary and medical risk factors
Feline Lower Urinary Tract Disease
Calcium oxalate
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 Disease
Calcium oxalate
Nutrient profile
Potassium citrate
Urinary pH 6.6-6.8
Increased moisture
Pyridoxine (vitamin B6)
Soluble fiber
Moderate magnesium
Feline Lower Urinary Tract Disease
Struvite
Mg - NH4 - PO4 . 6H20
Magnesium
Ammonium
Anionic phosphate
Feline Lower Urinary Tract Disease
Struvite
Dietary management
 Reduced magnesium
Less than 20 mg/100 kcal ME
Less than 0.1% (dry matter)
 Increased diuresis
Water
Sodium
Feline Lower Urinary Tract Disease
Struvite
Dietary management
 Acid urine pH
 Avoid over-acidification
Metabolic acidosis
Renal disease
 Dissolution - urinary pH 5.9 - 6.1
 Prevention - normal acid urinary pH 6.2-6.4
Canine and Feline Urolithiasis
Urinary acidification
Decrease in urine pH from 8.5 to 5.5
+
 NH4 - 1000 x Increase
3 PO4
- 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
Feline Lower Urinary Tract Disease
Struvite
Dietary management
 Feed calculolytic diet exclusively
 1 - 2 months
 Longer if UTI is present
 If no reduction of calculi after 2 months,
surgery should be considered
Canine Urolithiasis
Struvite
Mg - NH4 - PO4 . 6H20
Crystal
Magnesium
Ammonium
Anionic phosphate
Diet
Magnesium
Protein
Phosphorus
Canine Urolithiasis
Struvite - Dissolution
Nutrients
Minimize protein
Reduce magnesium
Reduce phosphorus
Stimulate water intake
Increase sodium
Acidify urine
Canine Urolithiasis
Struvite - Dissolution
% DM
 Protein
 Magnesium
 Phosphorus
 Sodium
 Urinary pH
Normal
Foods
15 - 60
0.03 - 0.27
0.41 - 2.43
0.11 - 2.22
6.7 - 8.3
Calculolytic
Diet
7.6
0.02
0.10
1.28
5.9 - 6.1
Canine Urolithiasis
Struvite - Dissolution
Feed calculolytic diet exclusively
Treat urinary tract infection
Continue treatment till 4 weeks after
radiographic dissolution
Canine Urolithiasis
Struvite - Dissolution
Monthly evaluation
 Radiography
 Serum urea nitrogen (SUN)
 Urinalysis: crystals, culture bacteria
Owner compliance
 Struvite crystalluria
 SUN > 10 mg/dl
Canine Urolithiasis
Struvite - Dissolution
Reasons for failure
Insufficient time
Non-compliance by owner
Urinary tract infection
Non-Struvite urolith
Canine Urolithiasis
Struvite - Treatment
Indications for surgery
Obstruction
Anatomical defects
No response to medical treatment
Diet is contraindicated
Canine Urolithiasis
Struvite - Treatment
Diet contra-indications
Sodium retention
Heart failure, hypertension, liver disease, nephrotic
syndrome
Increased protein requirements
Pregnancy, lactation, growth, cats
Acidifing diet
Renal insuff., metabolic acidosis, growth, Ca-ox.
Canine Urolithiasis
Struvite - Prevention
Prevention of recurrence
Urinary acidification
Moderate reduction of protein, Mg, P
Moderate sodium level
Canine Urolithiasis
Calcium oxalate
Treatment
Surgery
Hydropropulsion
Canine Urolithiasis
Calcium oxalate
Verminderen uitscheiding bouwstenen
• Calcium
Ca-opname + Calciurie
Vitamine D3: Ca aborptie + indirect calciurie
P: te laag: stimulatie Vit D3
Na: stimulatie calciurie
Zure urine: stimulatie calciurie
• Oxalaat: spinazie, rubarber, chocolade
Canine Urolithiasis
Calcium oxalate
Verhogen inhibitoren
• Magnesium
• pH urine:
Alkalinserend: vb. K-citraat
Dierlijke eiwitten verzuren: hoge eiwitopname
vermijden
Andere: wateropname
Canine Urolithiasis
Calcium oxalate - Prevention
Prevention of recurrence
 Avoid excessive intake of protein
 Low calcium intake
 Low oxalate intake
 Low sodium intake
 Avoid urinary acidification
 Potassium citrate
Canine Urolithiasis
Calcium oxalate
Prevention of recurrence
Advanced renal failure diet
Canine Urolithiasis
Ammonium urate - Treatment
Dissolution
Dietary management
Allopurinol
Urinary tract infection
Canine Urolithiasis
Ammonium urate - Treatment
Allopurinol
Meat diets

Xanthine
+
Xanthine oxidase
Purine / Pyrimidine
(Nucleic acids &
Cell nuclei)
Uric acid
+
Allantoin
Uricase
(Defect in Dalmatians)
Canine Urolithiasis
Ammonium urate - Treatment
Dietary management
Ammonium - Low protein
Urate - Low purine
Muscle & organ tissue = high in purines
Egg & casein = low in purines
Alkalinize urine
Canine Urolithiasis
Alkalinize urine
+
H
+
NH4
NH3
+
Decreases NH4 concentration
Canine Urolithiasis
Ammonium urate - Treatment
Advanced renal failure diet
8 - 11 weeks required for dissolution
Monitor for urethral obstruction
Canine Urolithiasis
Ammonium urate - Prevention
Prevention of recurrence
Advanced renal failure diet
Low in protein & purines
Alkalinizing the urine
Allopurinol
Canine Urolithiasis
Cystine - Composition
= Cysteïne - Cysteïne
Genetische afwijking: gestoorde
reabsorptie van
Cystine: weinig oplosbaar
Ornithine
Lysine
wateroplosbaar
Alanine
Canine Urolithiasis
Cystine - Treatment
Surgery
Dissolution
Canine Urolithiasis
Cystine - Treatment
Dissolution
Dietary management
D-Penicillamine
2-MPG (Thiola)
Urinary tract infection
Canine Urolithiasis
Cystine - Treatment
Dietary management
Low Protein
Low in cystine, cysteine
Low sodium
Alkalinize urine
Advanced renal failure diet
Canine Urolithiasis
Cystine - Treatment
Dissolution
Cystine + D-Penicillamine or 2-MPG

D-Penicillamine-Cysteine
2-MPG - Cysteine
Solubility x 50
Canine Urolithiasis
Cystine - Treatment
Urine pH
Solubility
1.0 x
1.3 x
2.0 x
Urine pH
7.0
7.5
8.0
Canine Urolithiasis
Cystine - Prevention
Prevention of recurrence
Inborn error do not breed
Advanced renal failure diet
2-MPG 15 mg/kg BID
or
D-Penicillamine 10 mg/kg BID
Gemengde stenen
Ca-oxalaat & struviet
Primair vs. secundair
Ca-oxalaat
irritatie - ontsteking
secundaire infectie
Struvite
ureasevorming
pH & NH4+
Canine and Feline Urolithiasis
Conclusion
Correct differential diagnosis is
important for success of treatment
Urolithiasis has an underlying cause
which should be further investigated
Dietary versus surgical treatment is
decided based on stone type, location and
medical factors.
Canine and Feline Urolithiasis
Conclusion
One diet can not work for all types of
uroliths
Preventive diets should provide balanced
nutrition
Avoid over-acidification of the urine