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)
PROCEDURES Medical records were reviewed for Miniature Schnauzers, Bichons Frises, and Shih Tzus that were examined between January 2001 and November 2014 for another urolithiasis study or for a urolith removal procedure. Dogs with CaOx uroliths were classified as cases. Dogs without a history of urinary tract disease and with no evidence of radiopaque uroliths on abdominal radiographs were classified as controls. Each case was matched with 1 control on the basis of age (± 2 years), sex, and breed. Body condition score and urinalysis results were compared between cases and controls, and the relationship between BCS and urine pH was analyzed.
RESULTS Median BCS was significantly greater for cases than controls, although the proportion of overweight dogs did not differ significantly between the 2 groups. Urine pH was negatively associated with age, but was not associated with BCS or the presence of CaOx uroliths. Cases infrequently had acidic urine or CaOx crystalluria but frequently had hematuria and proteinuria.
CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that dogs with CaOx uroliths had a greater median BCS than control dogs, but the clinical importance of that finding was unclear. Acidic urine and CaOx crystalluria were uncommon and not adequate predictors of CaOx urolith status. Hematuria and proteinuria were commonly observed in dogs with CaOx urolithiasis, but they are not pathognomonic for that condition.
To document the clinical signs, diagnosis, and treatment of urolithiasis in green iguanas (Iguana iguana) and to report on the composition of uroliths from green iguanas submitted to the Minnesota Urolith Center for analysis.
21 green iguanas with urolithiasis.
Medical record databases of multiple veterinary teaching hospitals were searched from 1996 through 2020. Emails were sent to all facilities that submitted a urolith from a green iguana to the Minnesota Urolith Center from 1996 through 2020. Signalment; presenting complaint; physical examination findings; hematologic, biochemical, and diagnostic imaging findings; treatment; necropsy results; and survival times were described for each patient.
Iguanas most commonly presented with nonspecific clinical signs, but 9 of the 21 iguanas had clinical signs associated with the urogenital tract. Twelve iguanas had a palpable mass in the caudal coelom. All uroliths were visible on radiographs. Surgery was performed on 15 iguanas; 3 died secondary to intra- or postoperative complications. Iguanas that underwent surgery had a median survival time of 39 months. Necropsy was performed on 5 iguanas, and urolithiasis contributed to the decision to euthanize or was the cause of death for 4. Uroliths from 132 iguanas were analyzed, and all were composed of 100% uric acid salts.
Green iguanas with urolithiasis may not have clinical signs or physical examination findings associated with the urinary system, and hematologic and biochemical abnormalities are nonspecific. Green iguanas should be routinely examined for uroliths, and surgical treatment should be pursued.
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 effects of storage temperature
and time on pH and specific gravity of and number
and size of crystals in urine samples from dogs
Design—Randomized complete block design.
Animals—31 dogs and 8 cats.
Procedure—Aliquots of each urine sample were analyzed
within 60 minutes of collection or after storage
at room or refrigeration temperatures (20 vs 6°C [68
vs 43°F]) for 6 or 24 hours.
Results—Crystals formed in samples from 11 of 39
(28%) animals. Calcium oxalate (CaOx) crystals
formed in vitro in samples from 1 cat and 8 dogs.
Magnesium ammonium phosphate (MAP) crystals
formed in vitro in samples from 2 dogs. Compared
with aliquots stored at room temperature, refrigeration
increased the number and size of crystals that
formed in vitro; however, the increase in number and
size of MAP crystals in stored urine samples was not
significant. Increased storage time and decreased
storage temperature were associated with a significant
increase in number of CaOx crystals formed.
Greater numbers of crystals formed in urine aliquots
stored for 24 hours than in aliquots stored for 6
hours. Storage time and temperature did not have a
significant effect on pH or specific gravity.
Conclusions and Clinical Relevance—Urine samples
should be analyzed within 60 minutes of collection to
minimize temperature- and time-dependent effects on
in vitro crystal formation. Presence of crystals observed
in stored samples should be validated by reevaluation of
fresh urine. (J Am Vet Med Assoc 2003;222:176–179)
Objective—To identify demographic or signalment factors associated with calcium carbonate urolith formation in goats.
Design—Retrospective case series and case-control study.
Animals—354 goats with calcium carbonate uroliths (case animals) and 16,366 goats without urinary tract disease (control animals).
Procedures—Medical records of the Minnesota Urolith Center were reviewed to identify case goats for which samples were submitted between January 1, 1984, and December 31, 2012. Control goats evaluated at US veterinary teaching hospitals in the same time period were identified by searching Veterinary Medical Database records. Age, breed, sex, reproductive status, geographic location, season, and anatomic location of collected uroliths were analyzed to identify risk or protective factors associated with calcium carbonate urolithiasis.
Results—Nigerian dwarf goats had higher odds of developing calcium carbonate uroliths than did Pygmy goats (reference group). Several breeds had lower odds of this finding, compared with Pygmy goats; odds were lowest for mixed, Anglo-Nubian, and Toggenburg breeds. Breeds of African origin (Pygmy, Nigerian Dwarf, and Boer) comprised 146 of 275 (53%) case goats with data available. Goats of African descent had a higher risk of developing calcium carbonate uroliths than did goats of non-African descent (reference group). Males and neutered goats had higher odds of calcium carbonate urolithiasis, compared with females and sexually intact goats, respectively. Age category, geographic location, and season were associated with detection of calcium carbonate uroliths.
Conclusions and Clinical Relevance—Goats with calcium carbonate uroliths were typically neutered males, > 1 year of age, and of African descent. This study identified factors associated with calcium carbonate urolithiasis in goats; however, these associations do not allow conclusions regarding cause-and-effect relationships.
Objective—To characterize the efficacy and safety of laser lithotripsy in the fragmentation of urocystoliths and urethroliths for removal in dogs.
Design—Prospective case series.
Animals—100 dogs with naturally occurring urocystoliths and urethroliths.
Procedures—Via cystoscopy, laser lithotripsy was performed to fragment uroliths. Basket retrieval and voiding urohydropropulsion were used to remove fragments. Postprocedural contrast cystography was performed to assess efficacy and safety. In 40 dogs, midstream urine samples were collected just prior to laser lithotripsy (day 0) and on days 1, 3, and 11 after laser lithotripsy to assess inflammation.
Results—Urolith removal was complete in 82% of dogs (52/66 with only urocystoliths, 17/17 with only urethroliths, and 13/17 with urocystoliths and urethroliths). Urolith removal was incomplete in 18 dogs; of these dogs, 9, 6, and 3 had urolith fragments ≥ 3 mm, 1 to < 3 mm, and < 1 mm in diameter, respectively. Sex (female) was the most significant predictor for success. Median procedure time was 72 minutes. Two dogs developed urinary tract obstruction following laser lithotripsy. Hematuria was detected in 53% of dogs on day 0 and in 84%, 13%, and 3% of dogs on days 1, 3, and 11, respectively. Leukocyturia was detected in 13% of dogs on day 0 and in 47%, 0%, and 3% of dogs on days 1, 3, and 11, respectively.
Conclusions and Clinical Relevance—Results suggested that use of laser lithotripsy was a safe and effective alternative to surgical removal of urocystoliths and urethroliths in dogs.
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 confirm that the predominant mineral type in naturally occurring uroliths in ferrets is struvite; to determine whether age, breed, sex, reproductive status, geographic location, season, and anatomic location are risk factors associated with urolith formation in ferrets; to compare features of struvite uroliths in cats with those in ferrets; and to determine whether there is a logical evidence-based rationale for clinical trials of the safety and efficacy of diet-induced dissolution of struvite uroliths in ferrets.
Design—Retrospective case-control study.
Animals—408 ferrets with uroliths (272 struvite uroliths) from the Minnesota Urolith Center, and 6,528 control ferrets from the Veterinary Medical Database.
Procedures—Historical information was obtained about each ferret. The association between proposed risk factors and outcome (struvite urolith formation) was assessed.
Results—Sterile struvite was the predominant mineral in uroliths in ferrets. Neutered male ferrets had a significantly increased risk of developing sterile struvite uroliths. A significant association was also found between increasing age and the detection of struvite uroliths. Struvite uroliths in ferrets were more likely to be retrieved from the lower urinary tract than from the upper urinary tract.
Conclusions and Clinical Relevance—Knowledge of predominant mineral type in uroliths along with insight into etiologic, demographic, and environmental risk and protective factors for urolithiasis may facilitate development of surveillance strategies that result in earlier detection of uroliths in ferrets. Modification of risk factors, including dietary risk factors, may help to minimize urolith formation, dissolve existing uroliths, and minimize urolith recurrence.