Objective—To evaluate the effect of dietary supplementation
with sodium chloride (NaCl) on urinary calcium
excretion, urine calcium concentration, and urinary
relative supersaturation (RSS) with calcium
Animals—6 adult female healthy Beagles.
Procedure—By use of a crossover study design, a
canned diet designed to decrease CaOx urolith recurrence
with and without supplemental NaCl (ie, 1.2%
and 0.24% sodium on a dry-matter basis, respectively)
was fed to dogs for 6 weeks. Every 14 days, 24-
hour urine samples were collected. Concentrations of
lithogenic substances and urine pH were used to calculate
values of urinary RSS with CaOx.
Results—When dogs consumed a diet supplemented
with NaCl, 24-hour urine volume and 24-hour urine
calcium excretion increased. Dietary supplementation
with NaCl was not associated with a change in urine
calcium concentration. However, urine oxalate acid
concentrations and values of urinary RSS with CaOx
were significantly lower after feeding the NaCl-supplemented
diet for 28 days.
Conclusions and Clinical Relevance—Dietary supplementation
with NaCl in a urolith-prevention diet
decreased the propensity for CaOx crystallization in
the urine of healthy adult Beagles. However, until
long-term studies evaluating the efficacy and safety of
dietary supplementation with NaCl in dogs with CaOx
urolithiasis are preformed, we suggest that dietary
supplementation with NaCl be used cautiously. (Am J
Vet Res 2005;66:319–324)
Objective—To evaluate urine concentrations of glycosaminoglycans, Tamm-Horsfall glycoprotein, and nephrocalcin in cats fed a diet formulated to prevent calcium oxalate uroliths.
Animals—10 cats with calcium oxalate urolithiasis.
Procedures—In a previous study conducted in accordance with a balanced crossover design, cats were sequentially fed 2 diets (the diet each cat was consuming prior to urolith detection and a diet formulated to prevent calcium oxalate uroliths). Each diet was fed for 8 weeks. At the end of each 8-week period, a 72-hour urine sample was collected. Concentrations of glycosaminoglycans, Tamm-Horsfall glycoprotein, and the 4 isoforms of nephrocalcin in urine samples collected during that previous study were measured in the study reported here.
Results—Diet had no effect on the quantity of Tamm-Horsfall glycoprotein and nephrocalcin in urine. However, the urine concentration of glycosaminoglycans was significantly higher during consumption of the urolith prevention diet.
Conclusions and Clinical Relevance—Feeding a urolith prevention diet increased the urine concentration of glycosaminoglycans, which are glycoprotein inhibitors of growth and aggregation of calcium oxalate crystals.
Objective—To test the hypothesis that feline calcium
oxalate uroliths are intrinsically more resistant to comminution
via shock wave lithotripsy (SWL) than canine
calcium oxalate uroliths through comparison of the
fragility of canine and feline uroliths in a quantitative
in vitro test system.
Sample Population—Calcium oxalate uroliths (previously
obtained from dogs and cats) were matched by
size and mineral composition to create 7 pairs of
uroliths (1 canine and 1 feline urolith/pair).
Procedure—Uroliths were treated in vitro with 100
shock waves (20 kV; 1 Hz) by use of an electrohydraulic
lithotripter. Urolith fragmentation was quantitatively
assessed via determination of the percentage
increase in projected area (calculated from the digital
image area of each urolith before and after SWL).
Results—After SWL, canine uroliths (n = 7) fragmented
to produce a mean ± SD increase in image area of 238
± 104%, whereas feline uroliths (7) underwent significantly
less fragmentation (mean image area increase of
78 ± 97%). The post-SWL increase in fragment image
area in 4 of 7 feline uroliths was < 50%, whereas it was
> 150% in 6 of 7 canine uroliths.
Conclusions and Clinical Relevance—Results indicate
that feline calcium oxalate uroliths are less susceptible
to fragmentation via SWL than canine calcium oxalate
uroliths. In some cats, SWL may not be efficacious for
fragmentation of calcium oxalate nephroliths or
ureteroliths because the high numbers of shock waves
required to adequately fragment the uroliths may cause
renal injury. (Am J Vet Res 2005;66:1651–1654)
Objective—To identify factors in dry diets associated
with the occurrence of calcium oxalate (CaOx)
uroliths in dogs.
Animals—600 dogs with CaOx uroliths and 898 dogs
without urinary tract diseases.
Procedure—Univariate and multivariate logistic
regression were performed.
Results—Compared with diets with the highest concentrations
of sodium, dry diets with the lowest concentrations
of sodium, phosphorus, calcium, chloride,
protein, magnesium, or potassium were linearly associated
with increased risk of CaOx urolith formation.
Significant nonlinear associations between increased
occurrence of CaOx uroliths and urine acidifying
potential and low moisture content were observed.
Significant nonlinear associations between decreased
occurrence of CaOx uroliths and carbohydrate and
fiber contents were observed. A significant association
between the occurrence of CaOx uroliths and
dietary fat was not observed.
Conclusions and Clinical Relevance—Results suggest
that dry diets formulated to contain high concentrations
of protein, calcium, phosphorus, magnesium,
sodium, potassium, and chloride may minimize formation
of CaOx uroliths. In addition, comparison of risk
and protective factors of various diet ingredients fed to
dogs with CaOx uroliths suggests that although similar
findings were observed in canned and dry formulations,
in general, greater risk is associated with dry formulations.
However, before these hypotheses about
dietary modifications are adopted by food manufacturers,
they must be investigated by use of appropriately
designed clinical studies of dogs with CaOx urolithiasis.
(Am J Vet Res 2002;63:330–337)
Objective—To identify dietary factors in commercially
available canned foods associated with the development
of calcium oxalate (CaOx) uroliths in dogs.
Animals—117 dogs with CaOx uroliths and 174 dogs
without urinary tract disease.
Procedure—Case dogs were those that developed
CaOx uroliths submitted to the Minnesota Urolith
Center for quantitative analysis between 1990 and
1992 while fed a commercially available canned diet.
Control dogs were those without urinary tract disease
evaluated at the same veterinary hospital just prior to
or immediately after each case dog. A content-validated
multiple-choice questionnaire was mailed to
each owner of case and control dogs with the permission
of the primary care veterinarian. Univariate
and multivariate logistic regressions for each dietary
component were performed to test the hypothesis
that a given factor was associated with CaOx urolith
Results—Canned foods with the highest amount of
protein, fat, calcium, phosphorus, magnesium, sodium,
potassium, chloride, or moisture were associated
with a decreased risk of CaOx urolith formation, compared
with diets with the lowest amounts. In contrast,
canned diets with the highest amount of carbohydrate
were associated with an increased risk of
CaOx urolith formation.
Conclusions and Clinical Relevance—Feeding
canned diets formulated to contain high amounts of
protein, fat, calcium, phosphorus, magnesium, sodium,
potassium, chloride, and moisture and a low
amount of carbohydrate may minimize the risk of
CaOx urolith formation in dogs. (Am J Vet Res 2002;63:163–169)