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 urate uroliths
are uncommonly detected in female Dalmatians,
compared with males.
Sample Population—Medical records of dogs evaluated
at veterinary teaching hospitals in North America
from 1981 to 2002 and compiled by the Veterinary
Medical Database, and records of dogs with uroliths
submitted for quantitative analyses to the Minnesota
Urolith Center from 1981 to 2002.
Procedures—Crude odds ratios (ORs) and 95% confidence
intervals were calculated to assess whether
sex (male vs female) was a risk factor for urate
Results—In Dalmatians evaluated by veterinary
teaching hospitals in North America, males were
more likely (OR, 13.0) to form uroliths, compared with
females. In Dalmatians that formed uroliths analyzed
by the Minnesota Urolith Center, males were more
likely (OR, 14.0) to form urate uroliths, compared with
females. In all dogs (Dalmatian and non-Dalmatian)
that formed uroliths analyzed by the Minnesota
Urolith Center, males were also more likely (OR, 48.0)
to form urate uroliths, compared with females.
Conclusions and Clinical Relevance—When conducting
studies and formulating generalities about
urate urolithiasis in Dalmatians, it is important to consider
sex-related differences in urolith occurrence.
Long-term dietary or drug protocols designed to minimize
formation of urate uroliths in male Dalmatians
may not be warranted in female Dalmatians. (J Am
Vet Med Assoc 2005;227:565–569)
Objective—To compare efficacy, required resources, and perioperative complications between laser lithotripsy and cystotomy for urolith (ie, urocystoliths and urethroliths) removal in dogs.
Design—Retrospective case-control study.
Animals—66 dogs with urolithiasis treated by laser lithotripsy (case dogs) and 66 dogs with urolithiasis treated by cystotomy (control dogs).
Procedures—Medical records were reviewed. Complete urolith removal rate, resources (ie, duration of hospitalization, procedure time, anesthesia time, procedure cost, and anesthesia cost), and complications (ie, hypotension, hypothermia, incomplete urolith removal, and requirement of an ancillary procedure) were compared between cystotomy group dogs and lithotripsy group dogs.
Results—Duration of hospitalization was significantly shorter for lithotripsy group dogs, compared with cystotomy group dogs. Procedure time was significantly shorter for cystotomy group dogs, compared with lithotripsy group dogs. Cost of anesthesia was significantly less for cystotomy group dogs, compared with lithotripsy group dogs. No significant differences were found between cystotomy group dogs and lithotripsy group dogs with regard to urolith removal rate, procedure cost, anesthesia time, or any of the evaluated complications.
Conclusions and Clinical Relevance—Laser lithotripsy is a minimally invasive procedure that has been shown to be safe and effective in the removal of urocystoliths and urethroliths in dogs. No significant differences were found in the required resources or complications associated with laser lithotripsy, compared with cystotomy, for removal of uroliths from the lower portions of the urinary tract of dogs. Laser lithotripsy is a suitable, minimally invasive alternative to surgical removal of urethroliths and urocystoliths in dogs.
Objective—To identify demographic factors associated with urate urolithiasis in cats and determine whether the rate of urolith submission to a laboratory had changed over time.
Design—Case series and case-control study.
Animals—Cases consisted of 5,072 cats with urate uroliths submitted to the Minnesota Urolith Center between January 1, 1981, and December 31, 2008. Controls consisted of 437,228 cats without urinary tract diseases identified in records of the Veterinary Medical Database during the same period.
Procedures—Information on cat breed, age, sex, reproductive status, and location of uroliths was used to identify risk factors. Changes in annual urolith submission rates were evaluated.
Results—Purebred cats had significantly higher odds of developing urate uroliths than did cats of mixed breeding (reference group). On the other hand, cats of the Abyssinian, American Shorthair, Himalayan, Manx, and Persian breeds had significantly lower odds of developing urate uroliths than did mixed breeds. Neutered cats were 12 times as likely to develop urate uroliths as were sexually intact cats. Cats in all age groups had significantly increased odds of developing urate uroliths, compared with cats < 1 year of age (reference group). Cats ≥ 4 but < 7 years of age had the highest odds of all groups and were 51 times as likely to develop urate uroliths as were cats < 1 year of age. Urolith submission rates did not change significantly with time.
Conclusions and Clinical Relevance—Findings of this study suggested that the typical cat with urate uroliths was a purebred neutered cat, 4 to 7 years old, with uroliths in the bladder or urethra. This information may be helpful in predicting mineral composition of uroliths in vivo. However, no conclusions can be made regarding cause-and-effect relationships.
Objective—To determine whether hydrochlorothiazide
(HCTZ) reduces urinary calcium excretion in
dogs with calcium oxalate urolithiasis.
Animals—8 dogs with calcium oxalate urolithiasis.
Procedure—4 treatment protocols were evaluated in
each dog (a low calcium, low protein diet designed to
prevent calcium oxalate urolith formation with and
without administration of HCTZ [2 mg/kg (0.9 mg/lb)
of body weight, PO, q 12 h] and a maintenance diet
with higher quantities of protein and calcium with and
without administration of HCTZ). At the end of each 2-week treatment period, 24-hour urine samples were collected. Blood samples were collected during the
midpoint of each urine collection period. Analysis of
variance was performed to evaluate the effects of
HCTZ and diet on urine and serum analytes.
Results—Hydrochlorothiazide significantly decreased
urine calcium and potassium concentration and excretion.
Hydrochlorothiazide also significantly decreased
serum potassium concentration. Compared with the
maintenance diet, the urolith prevention diet significantly
decreased urine calcium and oxalic acid concentration
and excretion. Dogs consuming the urolith
prevention diet had significantly lower serum concentrations
of albumin and urea nitrogen.
Conclusions and Clinical Relevance—Administration
of HCTZ decreased urine calcium excretion
in dogs with a history of calcium oxalate urolith formation.
The greatest reduction in urine calcium concentration
and excretion was achieved when dogs
received HCTZ and the urolith prevention diet.
Results of this study suggest that the hypocalciuric
effect of HCTZ will minimize recurrence of calcium
oxalate urolith formation in dogs; however, long-term
controlled clinical trials are needed to confirm the
safety and effectiveness of HCTZ. (J Am Vet Med
Objective—To determine whether breed, age, sex, or
reproductive status (ie, neutered versus sexually
intact) was associated with the apparent increase in
prevalence of calcium oxalate (CaOx) uroliths and the
decrease in prevalence of magnesium ammonium
phosphate (MAP) uroliths in cats over time.
Animals—Case cats consisted of cats with CaOx (n
= 7,895) or MAP (7,334) uroliths evaluated at the
Minnesota Urolith Center between 1981 and 1997.
Control cats consisted of cats without urinary tract
disease admitted to veterinary teaching hospitals in
the United States and Canada during the same period
Procedure—Univariate and multivariate logistic
regression were performed.
Results—British Shorthair, Exotic Shorthair, Foreign
Shorthair, Havana Brown, Himalayan, Persian,
Ragdoll, and Scottish Fold cats had an increased risk
of developing CaOx uroliths, as did male cats and
neutered cats. Chartreux, domestic shorthair, Foreign
Shorthair, Himalayan, Oriental Shorthair, and Ragdoll
cats had an increased risk of developing MAP
uroliths, as did female cats and neutered cats. Cats
with CaOx uroliths were significantly older than cats
with MAP uroliths.
Conclusions and Clinical Relevance—Results suggest
that changes in breed, age, sex, or reproductive
status did not contribute to the apparent reciprocal
relationship between prevalences of CaOx and MAP
uroliths in cats during a 17-year period. However, cats
of particular breeds, ages, sex, and reproductive status
had an increased risk of developing CaOx and
MAP uroliths. (J Am Vet Med Assoc 2000;217:520–525)
Objective—To determine whether storage in neutral-buffered 10% formalin in vitro has any effect on the composition of biogenic minerals of canine and feline uroliths.
Design—Prospective in vitro study.
Sample Population—Canine and feline uroliths submitted to the Minnesota Urolith Center from 34 dogs and 27 cats.
Procedures—Submissions from each dog or cat consisted of multiple uroliths of a single mineral type. After retrieval from the urinary tract, none of the uroliths had been placed in a preservative before submission. Evaluated uroliths were exclusively composed of the following: only struvite (uroliths from 5 dogs and 5 cats), calcium oxalate (5 dogs and 5 cats), calcium phosphate apatite (5 dogs and 5 cats), cystine (5 dogs and 5 cats), ammonium urate (5 dogs and 5 cats), or silica (5 dogs). One urolith from each dog or cat was quantitatively analyzed by polarized light microscopy, infrared spectroscopy, or both. Another urolith from the same animal was immersed in 1 mL of neutral-buffered 10% formalin for 48 hours at room temperature (22.5°C). Uroliths exposed to formalin were then air-dried for 30 minutes, and the analysis was repeated.
Results—After exposure to formalin, a portion of every struvite urolith was transformed into newberyite. This was not observed with any other urolith mineral type. Quantitative mineral analysis of nonstruvite uroliths revealed no detectable change in mineral composition. However, 3 of 10 ammonium urate uroliths dissolved when placed in formalin.
Conclusions and Clinical Relevance—To avoid misdiagnosis of mineral composition, uroliths should not be immersed in formalin prior to analysis.
Objective—To determine whether nephrolithiasis was associated with an increase in mortality rate or in the rate of disease progression in cats with naturally occurring stage 2 (mild) or 3 (moderate) chronic kidney disease.
Design—Retrospective case-control study.
Animals—14 cats with stage 2 (mild) or 3 (moderate) chronic kidney disease (7 with nephroliths and 7 without).
Procedures—All cats were evaluated every 3 months for up to 24 months. Possible associations between nephrolithiasis and clinicopathologic abnormalities, incidence of uremic crises, death secondary to renal causes, and death secondary to any cause were evaluated.
Results—There were no clinically important differences in biochemical, hematologic, or urinalysis variables between cats with and without nephroliths at baseline or after 12 and 24 months of monitoring. No associations were detected between nephrolithiasis and rate of disease progression, incidence of uremic crises, or death.
Conclusions and Clinical Relevance—Results suggested that in cats with mild or moderate chronic kidney disease, nephrolithiasis was not associated with an increase in mortality rate or in the rate of disease progression. Findings support recommendations that cats with severe kidney disease and nephrolithiasis be managed without surgery.
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)