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Abstract

Objective

To determine whether morphology of single-mineral urocystoliths and age, sex, or breed data could be applied to facilitate radiographic and clinical urocystolith mineral type prediction, respectively, in dogs.

Sample Population

Database of 2,041 dogs with pure mineral composition urocystoliths.

Procedure

All uroliths were characterized according to geologic descriptive terminology and by breed, sex, and age of dog at time of sample submission. Summary statistics were used to compare features with specific mineral types. Observed trends were analyzed for statistical relevance between observed and expected frequencies for age, sex, color, size, shape, and surface, using the null hypothesis that differences by urocystolith mineral type did not exist. On the basis of expected breed occurrence derived by equations, the null hypothesis that urocystolith occurrence paralleled canine breed popularity was tested.

Results

Urocystoliths > 10 mm in any dimension were > 92% likely to be magnesium ammonium phosphate hexahydrate (MAP). Smooth, blunt-edged or faceted, and pyramidal urocystoliths were usually MAP. Jackstone shapes were almost always silica. Botryoidal (grape-like clusters) urocystoliths were likely to be oxalates. Breeds with high relative likelihood of urocystoliths included: English Bulldog, Pekingese, Pug, Welsh Corgi, and West Highland White Terrier. Breeds with low relative likelihood of urocystolith production included: German Shepherd Dog, Shar-Pei, and German Shorthaired Pointer. About 94% of urocystoliths produced in females or spayed females were MAP, whereas males and neutered males produced a greater assortment.

Conclusions and Clinical Relevance

For pure mineral composition urocystoliths, trends in mineral type among breeds and between sexes can be exploited clinically in the diagnosis and management of urolith-related disease. Size and shape, used in conjunction with age, breed, and sex, can facilitate pure urocystolith mineral type prediction. (Am J Vet Res 1998;59:379–387)

Free access
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)

Full access
in American Journal of Veterinary Research

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)

Full access
in American Journal of Veterinary Research

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)

Full access
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)

Full access
in Journal of the American Veterinary Medical Association

SUMMARY

Urine activity product ratios of uric acid, sodium urate, and ammonium urate and urinary excretion of metabolites were determined in 24-hour samples produced by 6 healthy Beagles during periods of consumption of a low-protein, casein-based diet (diet A) and a high-protein, meat-based diet (diet B). Comparison of effects of diet A with those of diet B revealed: significantly lower activity product ratios of uric acid (P = 0.025), sodium urate (P = 0.045), and ammonium urate (P = 0.0045); significantly lower 24-hour urinary excretion of uric acid (P = 0.002), ammonia (P = 0.0002), sodium (P = 0.01), calcium (P = 0.005), phosphorus (P = 0.0003), magnesium (P = 0.01), and oxalic acid (P = 0.004); significantly (P = 0.0001) higher 24-hour urine pH; and significantly (P = 0.01) lower endogenous creatinine clearance. These results suggest that consumption of diet A minimizes changes in urine that predispose dogs to uric acid, sodium urate, and ammonium urate urolithiasis.

Free access
in American Journal of Veterinary Research

SUMMARY

Urine activity product ratios of uric acid (aprua), sodium urate (aprna), and ammonium urate (aprau), and urinary excretion of 10 metabolites were determined in 24-hour urine samples produced by 6 healthy Beagles during periods of consumption of 4 diets containing approximately 11% protein (dry weight) and various protein sources: a 72% moisture, casein-based diet; a 10% moisture, egg-based diet; a 72% moisture, chicken-based diet; and a 71% moisture, chicken-based, liver-flavored diet. Significantly (P < 0.05) higher aprua, aprna, and aprau were observed when dogs consumed the egg-based diet, compared with the other 3 diets; there were no differences in these ratios among the other 3 diets.

Twenty-four-hour urinary excretions of chloride, potassium, phosphorus, and oxalic acid were significantly (P < 0.05) higher when dogs consumed the egg-based diet. Twenty-four-hour urinary excretions of sodium were significantly (P < 0.05) higher when dogs consumed the egg-based diet, compared with the casein-based diet and the chicken-based, liver-flavored diet, but were not significantly different between the egg-based diet and chicken-based diet. Twenty-four-hour urine volume was similar when dogs consumed the 4 diets. Twenty-four-hour endogenous creatinine clearance was significantly (P < 0.05 lower when dogs consumed the casein based diet there were no differences among the other 3 diets. Although consumption all diets was associated with production alkaline urine, the 24-hour urine pH was significantly (P < 0.05) higher when dogs consumed the egg-based diet.

These results suggest that use diets containing approximately 10.5% protein (dry weight) and 70 moisture protocols designed for dissolution and prevention urate uroliths may be beneficial. The source dietary protein in canned formulated diets does not appear significantly influence the saturation of urine with uric acid, sodium urate, or ammonium urate.

Free access
in American Journal of Veterinary Research

Objective

To test the hypothesis that breed, sex, and age of cats, and anatomic location of uroliths are risk factors for calcium oxalate and magnesium ammonium phosphate urolithiasis.

Design

Retrospective case-control study.

Sample Population

Records of 3,498 feline urolith accessions submitted between September 1982 and September 1992.

Procedure

Mineral composition of feline uroliths was quantitatively analyzed. Odds ratios and 95% confidence intervals were calculated for breed, sex, age, and urolith location as risk factors for calcium oxalate and magnesium ammonium phosphate urolith formation. The population at risk was defined as all cats for which that type of urolith had been submitted. The control population was all cats for which uroliths had been submitted, excluding cats with the type of urolith being evaluated.

Results

Burmese, Persian, and Himalayan breeds were at higher risk for developing calcium oxalate uroliths, but at reduced risk for developing magnesium ammonium phosphate uroliths. Compared with females, neutered male cats had a higher risk for developing calcium oxalate uroliths, but a reduced risk for developing magnesium ammonium phosphate uroliths. The risk for calcium oxalate urolith formation increased with age. One- to 2-year-old female cats had the highest risk for magnesium ammonium phosphate uroliths. Uroliths removed from the kidneys were more likely to be composed of calcium oxalate than of magnesium ammonium phosphate.

Clinical Implications

Breed, sex, and age of cats, and anatomic location of uroliths should be considered when evaluating risk of calcium oxalate and magnesium ammonium phosphate urolithiasis in urolith-forming cats. (J Am Vet Med Assoc 1996; 208:547–551)

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objectives

To determine bioavailability and pharmacokinetic parameters for allopurinol and its active metabolite, oxypurinol.

Animals

6 healthy, reproductively intact female Beagles, 4.9 to 5.2 years old, and weighing 9.5 to 11.5 kg.

Procedure

In the first part of the study, allopurinol was administered IV at a dosage of 10 mg/kg of body weight to 3 dogs and 5 mg/kg to 3 dogs; the sequence was then reversed. In the second part of the study, allopurinol was administered orally at a dosage of 15 mg/kg to 3 dogs and 7.5 mg/kg to 3 dogs; the sequence was then reversed. In the third part of the study, allopurinol was administered IV (10 mg/kg), orally (15 mg/kg) with food, and orally (15 mg/kg) without food. Plasma samples were obtained at timed intervals, and concentrations of allopurinol and oxypurinol were determined.

Results

Maximal plasma allopurinol concentration and area under plasma allopurinol and oxypurinol concentration-time curves were 2 times greater when dogs were given 10 mg of allopurinol/kg IV, compared with 5 mg/kg, and when dogs were given 15 mg of allopurinol/kg orally, compared with 7.5 mg/kg. Allopurinol elimination half-life, time to reach maximal plasma oxypurinol concentration, and oxypurinol elimination half-life were significantly greater when dogs received 10 mg of allopurinol/kg IV, compared with 5 mg/kg, and when dogs received 15 mg of allopurinol/kg orally, compared with 7.5 mg/kg.

Conclusions

Elimination of allopurinol is dependent on nonlinear enzyme kinetics. The bioavailability of allopurinol, and pharmacokinetic parameters of allopurinol and oxypurinol after oral administration of allopurinol, are not affected by administration with food.

Clinical Relevance

A dose threshold exists beyond which additional allopurinol would not substantially further inhibit xanthine oxidase activity. Oral administration of > 15 mg of allopurinol/kg to dogs would not be expected to result in greater reduction of plasma and urine uric acid concentrations. Also, allopurinol may be administered to dogs for dissolution or prevention of urate uroliths without regard to time of feeding. (Am J Vet Res 1997;58:504–510)

Free access
in American Journal of Veterinary Research

Summary

Data were evaluated from all dogs admitted to the University of Minnesota Veterinary Teaching Hospital (UMVTH) between June 1, 1981 and Dec 31, 1991. During this period, uroliths were retrieved and analyzed from 452 of 37,574 dogs admitted. The odds that uroliths from Bulldogs were composed of cystine were 32.3 times greater than for other breeds evaluated. The odds that a Bulldog admitted was affected with cystine uroliths were 154.1 times greater than for other breeds. Cystine uroliths were retrieved only from male Bulldogs. The odds that uroliths from Bulldogs were composed of urate were 7.9 times greater than for other breeds. The odds that a Bulldog admitted was affected with urate uroliths were 43.0 times greater than for other breeds. Male Bulldogs were 14.3 times more likely to be affected with urate uroliths than were females. The odds that uroliths from Dalmatians were composed of urate were 228.9 times greater than for other breeds. The odds that a Dalmatian admitted was affected with urate uroliths were 122.4 times greater than for other breeds. Male Dalmatians were 16.4 times more likely to be affected with urate uroliths than were females.

Data also were evaluated from files of canine uroliths submitted to the Minnesota Urolith Center for quantitative mineral analysis between June 1, 1981 and Dec 31, 1991. During this period, 94 of 11,188 uroliths analyzed were obtained from Bulldogs and 387 were obtained from Dalmatians. The odds that uroliths retrieved from Bulldogs were composed of cystine were 40.7 times greater than for other breeds. Cystine uroliths were retrieved only from male Bulldogs. The odds that uroliths retrieved from Bulldogs were composed of urate were 16.4 times greater than for other breeds. Although 88.6% of urate uroliths were retrieved from male Bulldogs, the odds ratios for males were not significantly different than for females. The odds that uroliths retrieved from Dalmatians were composed of urate were 162.4 times greater than for other breeds. Although 93.0% of urate uroliths were retrieved from male Dalmatians, the odds ratio for males was not significantly different than for females.

Free access
in Journal of the American Veterinary Medical Association