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Abstract

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 and cats.

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)

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in Journal of the American Veterinary Medical Association

Abstract

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.

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in Journal of the American Veterinary Medical Association

Abstract

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.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the prevalence of cystine uroliths in domestic ferrets with urolithiasis and determine whether age, breed, sex, reproductive status, anatomic location, and season are risk factors associated with cystine urolith formation.

Design—Retrospective cross-sectional case-control study.

Sample—Records of 435 ferrets (Mustela putorius furo) with uroliths submitted for analyses between 1992 and 2009, of which 70 were cystine uroliths.

Procedures—Specific descriptive information was obtained about each ferret to determine whether specific risk factors were associated with the development of cystine uroliths.

Results—Cystine uroliths comprised 70 of the 435 (16%) uroliths. Cystine uroliths were more common in male (n = 54) than in female (16) ferrets. All cystine uroliths were retrieved from the lower portion of the urinary tract (bladder and urethra [n = 67]) or were voided (3); none of the uroliths were retrieved from the upper portion of the urinary tract (kidney and ureters).

Conclusions and Clinical Relevance—Awareness of the prevalence of cystine uroliths along with knowledge of etiologic, demographic, and environmental risk and protective factors for urolithiasis may facilitate development of surveillance strategies that result in earlier detection of cystinuria. Genetic factors associated with this disease have not yet been reported in ferrets, but a familial pattern of inheritance determined to be a major underlying factor in cystine urolithiasis in dogs and humans suggests that this may be a factor in ferrets and that the parent stock of ferrets in the present study may have been inbred.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To test the hypothesis that breed, age, sex, body condition, and environment are risk factors for development of calcium oxalate uroliths in dogs.

Design—Case-control study.

Animals—1,074 dogs that formed calcium oxalate uroliths and 1,724 control dogs that did not have uroliths.

Procedure—A validated multiple-choice questionnaire was designed to collect information from veterinarians and owners within 1 year of the date of urolith detection concerning signalment and environment of the dogs. Univariate and multivariate analyses were performed to calculate odds ratios to assess whether breed, age, sex, body condition, and environment were risk factors for calcium oxalate urolith formation.

Results—Middle-aged (8- to 12-year-old) castrated male dogs had increased risk for formation of calcium oxalate uroliths. Urolith formation was also associated with increasing age. Dogs of certain breeds, including Miniature and Standard Schnauzer, Lhasa Apso, Yorkshire Terrier, Bichon Frise, Shih Tzu, and Miniature and Toy Poodle, had increased risk for developing calcium oxalate uroliths. Overweight dogs also had increased risk.

Conclusions and Clinical Relevance—Knowledge of patient and environmental risk factors for development of calcium oxalate uroliths may facilitate development of surveillance strategies that result in earlier detection of this disease. Modification of environmental factors and body weight may minimize calcium oxalate urolith formation and recurrence. (J Am Vet Med Assoc 2000;217:515–519)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To identify dietary factors associated with the increase in occurrence of calcium oxalate (CaOx) uroliths and the decrease in occurrence of magnesium ammonium phosphate (MAP) uroliths in cats.

Design—Case-control study.

Animals—173 cats with CaOx uroliths, 290 cats with MAP uroliths, and 827 cats without any urinary tract diseases.

Procedure—Univariate and multivariate logistic regression were performed.

Results—Cats fed diets low in sodium or potassium or formulated to maximize urine acidity had an increased risk of developing CaOx uroliths but a decreased risk of developing MAP uroliths. Additionally, compared with the lowest contents, diets with the highest moisture or protein contents and with moderate magnesium, phosphorus, or calcium contents were associated with decreased risk of CaOx urolith formation. In contrast, diets with moderate fat or carbohydrate contents were associated with increased risk of CaOx urolith formation. Diets with the highest magnesium, phosphorus, calcium, chloride, or fiber contents and moderate protein content were associated with increased risk of MAP urolith formation. On the other hand, diets with the highest fat content were associated with decreased risk of MAP urolith formation.

Conclusions and Clinical Relevance—Results suggest that diets formulated to contain higher protein, sodium, potassium, moisture, calcium, phosphorus, and magnesium contents and with decreased urine acidifying potential may minimize formation of CaOx uroliths in cats. Diets formulated to contain higher fat content and lower protein and potassium contents and with increased urine acidifying potential may minimize formation of MAP uroliths. (J Am Vet Med Assoc 2001;219:1228–1237)

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in Journal of the American Veterinary Medical Association

Abstract

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)

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in American Journal of Veterinary Research

Abstract

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 formation.

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)

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in American Journal of Veterinary Research

Abstract

Objective—To determine whether high systolic blood pressure (SBP) at the time of initial diagnosis of chronic renal failure in dogs was associated with increased risk of uremic crisis, risk of dying, or rate of decline in renal function.

Design—Prospective cohort study.

Animals—45 dogs with spontaneous chronic renal failure.

Procedure—Dogs were assigned to 1 of 3 groups on the basis of initial SBP (high, intermediate, low); Kaplan-Meier and Cox proportional hazards methods were used to estimate the association between SBP and development of a uremic crisis and death. The reciprocal of serum creatinine concentration was used as an estimate of renal function.

Results—Dogs in the high SBP group were more likely to develop a uremic crisis and to die than were dogs in the other groups, and the risks of developing a uremic crisis and of dying increased significantly as SBP increased. A greater decrease in renal function was observed in dogs in the high SBP group. Retinopathy and hypertensive encephalopathy were detected in 3 of 14 dogs with SBP ≥ 180 mm Hg. Systolic blood pressure remained high in 10 of 11 dogs treated with antihypertensive drugs.

Conclusions and Clinical Relevance—Results suggested that initial high SBP in dogs with chronic renal failure was associated with increased risk of developing a uremic crisis and of dying. Further studies are required to determine whether there is a cause-and-effect relationship between high SBP and progressive renal injury and to identify the risks and benefits of antihypertensive drug treatment. (J Am Vet Med Assoc 2003;222:322–329)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine whether urine protein-to-creatinine ratio (UP:C) ≥ 1.0 at initial diagnosis of chronic renal failure (CRF) is associated with greater risk of development of uremic crises, death, and progression of renal failure in dogs.

Design—Prospective cohort study.

Animals—45 dogs with CRF.

Procedure—Dogs were prospectively assigned to 2 groups on the basis of initial UP:C < 1.0 or ≥ 1.0. The association between magnitude of proteinuria and development of uremic crises and death was determined before and after dogs with initial UP:C ≥ 1.0 were assigned to 3 subgroups and compared with dogs with initial UP:C < 1.0. Changes in reciprocal serum creatinine concentration were used to estimate decrease in renal function.

Results—Initially, dogs had similar clinical characteristics with the exception of systolic blood pressure and UP:C. Relative risks of development of uremic crises and death were approximately 3 times higher in dogs with UP:C ≥ 1.0, compared with dogs with UP:C < 1.0. Relative risk of adverse outcome was approximately 1.5 times higher for every 1-unit increment in UP:C. The decrease in renal function was of greater magnitude in dogs with UP:C ≥ 1.0, compared with dogs with UP:C < 1.0.

Conclusions and Clinical Relevance—Initial UP:C ≥ 1.0 in dogs with CRF was associated with greater risk of development of uremic crises and death, compared with dogs with UP:C < 1.0. Initial determinations of UP:C in dogs with naturally occurring CRF may be of value in refining prognoses. (J Am Vet Med Assoc 2005;226:393–400)

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in Journal of the American Veterinary Medical Association