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Abstract

Objective

To evaluate the influence of 3 diets used to dissolve or prevent ammonium urate uroliths in dogs, and a diet formulated for growth, on 24-hour excretions of uric acid, ammonia, net acid, titratable acid, bicarbonate, and creatinine: 24-hour urine volumes: pH values of 24-hour urine samples; plasma uric acid concentration; serum creatinine concentration; and endogenous creatinine clearance values.

Design

Randomized block.

Animals

Six reproductively intact female Beagles, 3.9 to 4.2 years old, weighing 8.5 to 11.1 kg.

Procedures

Four diets were evaluated for their ability to dissolve magnesium ammonium phosphate hexahydrate (struvite) uroliths (diet S); to minimize uric acid excretion (diet U); to minimize clinical signs associated with renal failure (diet K); and to promote growth in pups (diet P). Each diet was fed for 14 days; then 24-hour urine samples were collected. An adult maintenance diet was fed during a 7-day washout period.

Results

Consumption of diet U was associated with lowest plasma uric acid concentration, lowest 24-hour urinary uric acid, ammonia, titratable acid, and net acid excretions, lowest endogenous creatinine clearance values, highest 24-hour urinary bicarbonate excretion and urine pH values, and highest 24-hour urine volumes. Consumption of diet P was associated with opposite results; results of consumption of diets S and K were intermediate between those for diets U and P.

Conclusion

Consumption of diet U by healthy Beagles is associated with reduced magnitude of urinary excretion of uric acid and ammonia, with alkaluria, and with polyuria, which may be beneficial in the management of ammonium urate uroliths in dogs.

Clinical Relevance

Results support use of diet U for management of ammonium urate urolithiasis in dogs.(Am J Vet Res 1996;57:324-328)

Free access
in American Journal of Veterinary Research

SUMMARY

Hyperxanthinuria and xanthine uroliths have been recognized with increased frequency in dogs with ammonium urate uroliths that had been given allopurinol. We hypothesized that dietary modification might reduce the magnitude of uric acid and xanthine excretion in urine of dogs given allopurinol. To test this hypothesis, excretion of metabolites, volume, and pH were determined in 24-hour urine samples produced by 6 healthy Beagles during periods of allopurinol administration (15 mg/kg of body weight, PO, q 12 h) and consumption of 2 special purpose diets: a 10.4% protein (dry matter), casein-based diet and a 31.4% protein (dry matter), meat-based diet.

Significantly lower values of uric acid (P = 0.004), xanthine (P = 0.003), ammonia (P = 0.0002), net acid (P = 0.0001), titratable acid (P = 0.0002), and creatinine (P = 0.01) excreted during a 24-hour period were detected when dogs consumed the casein-based diet and were given allopurinol, compared with the 24-hour period when the same dogs consumed the meat-based diet and were given allopurinol. For the same 24-hour period, urine pH values, urine volumes, and urine bicarbonate values were significantly (P = 0.0004, P = 0.04, and P = 0.002, respectively) higher during the period when the dogs were fed the casein-based diet and given allopurinol than when they were fed the meat-based diet and given allopurinol. Endogenous creatinine clearance was significantly (P = 0.006) lower when dogs were fed the casein-based diet and given allopurinol than when they were fed the meat-based diet and given allopurinol. Significantly lower concentrations of plasma uric acid (P = 0.0001), plasma xanthine (P = 0.01), and serum urea nitrogen (P = 0.0001) were detected when dogs consumed the casein-based diet and were given allopurinol than when they consumed the meat-based diet and were given allopurinol. On the basis of these results, use of the casein-based diet and allopurinol in protocols designed for dissolution of urate uroliths may be beneficial in preventing hyperxanthinuria and xanthine urolith formation.

Free access
in American Journal of Veterinary Research

Summary

Urine uric acid-to-urine creatinine ratios (uua:uc), urine uric acid concentrations, urine uric acid concentrations corrected for glomerular filtration rate, and urinary uric acid fractional excretions were compared with 24-hour urinary uric acid excretions measured in 6 healthy adult female Beagles. Comparisons, using correlation analysis, were made when dogs consumed a 10.4% protein (dry weight), casein-based diet and a 31.4% protein (dry weight), meat-based diet. The uua:uc, urine uric acid concentrations corrected for glomerular filtration rate, and urinary uric acid fractional excretions were not reliable estimates of 24-hour urinary uric acid excretions during consumption of either diet. Urine uric acid concentrations in samples collected 2, 4, 6, and 24 hours after initiation of collection correlated with 24-hour urinary uric acid excretions when dogs consumed the casein-based diet; correlation was not found at any time interval when dogs consumed the meatbased diet. Therefore, determination of 24-hour urinary uric acid excretion is recommended because uua:uc are unreliable.

Free access
in American Journal of Veterinary Research

Summary

A technique called voiding urohydropropulsion has been developed that facilitates nonsurgical removal of urocystoliths. Voiding urohydropropulsion was performed in 11 dogs and 10 cats with urocystoliths. Urocystoliths were completely removed from 15 of 21 animals (5 female dogs, 3 male dogs, 5 female cats, and 1 male cat). The number of uroliths removed from any animal varied between 1 and 983. The mean time required to complete voiding urohydropropulsion in the 15 animals from which all uroliths were completely removed was 22 minutes. In 6 animals (2 female dogs, 3 female cats, and 1 male cat), not all urocystoliths were removed. Visible hematuria was induced in all animals as a consequence of voiding urohydropropulsion. In dogs, visible hematuria resolved within 4 hours. Dysuria was not induced by this technique in dogs. In many cats, visible hematuria and dysuria persisted for 1 to 2 days. One male cat developed urethral obstruction after we failed to remove a urolith from the bladder. The urolith was returned to the urinary bladder, and subsequently removed by cystotomy. Voiding urohydropropulsion is a simple and effective method that should be considered for removal of small urocystoliths from dogs and cats before cystotomy is performed.

Free access
in Journal of the American Veterinary Medical Association

SUMMARY

Epidemiologic data were evaluated from all dogs admitted to the University of Minnesota, Veterinary Teaching Hospital (UMVTH) between June 1981 and November 1989. Of 69,890 admissions, 2,077 were Miniature Schnauzers. Uroliths were retrieved from 63 of the 2,077 Miniature Schnauzers admitted. In 20 of the 63 urolith episodes, calcium oxalate was the predominant mineral identified. By comparison, calcium oxalate uroliths were identified in only 56 of the remaining 67,813 non-Miniature Schnauzer canine admissions. The odds that uroliths from Miniature Schnauzers were composed of calcium oxalate was 11.8 times greater than for other canine breeds evaluated at the UMVTH (95% confidence interval = 6.8 to 20.1).

Data also were evaluated from files of uroliths retrieved from dogs and submitted to the Minnesota Urolith Center for quantitative mineral analysis between June 1981 and November 1989. Of 3,930 uroliths analyzed, 615 (15.6%) uroliths were obtained from Miniature Schnauzers. Of the 615 uroliths, 175 (28.4%) were calcium oxalate. By comparison, only 550 (16.6%) of the remaining 3,315 from dogs of breeds other than Miniature Schnauzers were calcium oxalate. The odds that uroliths submitted for analysis were composed of calcium oxalate was 2 times greater for Miniature Schnauzers than for dogs of other breeds (95% confidence interval = 1.6 to 2.4).

Calcium oxalate uroliths were retrieved more frequently in males than females. The risk for males developing calcium oxalate uroliths was > 3 times the risk for females in both groups of data evaluated. The mean age of all Miniature Schnauzers admitted to the UMVTH with calcium oxalate uroliths was 9 years. Calcium oxalate uroliths were not detected in Miniature Schnauzers younger than 1.7 years.

Free access
in American Journal of Veterinary Research

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

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